šÆ TOP 15 Python Interview Questions Asked in 2026
(TCS ⢠Infosys ⢠Wipro ⢠Startups ā ye sab poochte hain!)
Save karo ā interview se pehle zaroor padho! š
āāāāāāāāāāāāāāāāāāāāāā
BASICS (Freshers ke liye must!)
1ļøā£ List vs Tuple?
ā List = mutable | Tuple = immutable
ā Tuple is faster & used for fixed data
2ļøā£ What are Python decorators?
ā Functions jo dusre functions wrap karte hain
ā @staticmethod, @classmethod, @property
ā Flask mein @app.route bhi ek decorator hai
3ļøā£ deepcopy vs shallow copy?
ā Shallow = reference copy (nested objects share)
ā Deep = completely new independent copy
ā import copy ā copy.deepcopy(obj)
4ļøā£ What is GIL in Python?
ā Global Interpreter Lock
ā Only ONE thread runs at a time in CPython
ā Use multiprocessing for true parallelism
5ļøā£ What are generators?
ā Use yield instead of return
ā Memory efficient ā values on demand
ā Perfect for large datasets
āāāāāāāāāāāāāāāāāāāāāā
INTERMEDIATE (Most asked in tech rounds!)
6ļøā£ List comprehension vs map() ā which is faster?
ā List comprehension is more readable & Pythonic
ā map() slightly faster for simple functions
7ļøā£ What is *args and **kwargs?
ā *args = variable positional arguments
ā **kwargs = variable keyword arguments
8ļøā£ Mutable vs Immutable data types?
ā Mutable: list, dict, set
ā Immutable: int, str, tuple, float
9ļøā£ What is __init__ vs __new__?
ā __new__ creates the object
ā __init__ initializes it (constructor)
š Python memory management?
ā Reference counting + Garbage collector
ā del keyword decrements reference count
āāāāāāāāāāāāāāāāāāāāāā
ADVANCED (For senior/experienced roles!)
1ļøā£1ļøā£ Lambda function?
ā Anonymous one-line function
ā square = lambda x: x**2
1ļøā£2ļøā£ OOPS in Python?
ā Class, Object, Inheritance, Polymorphism
ā Always give a real example (Bank, Car etc.)
1ļøā£3ļøā£ is vs == difference?
ā == checks value | is checks memory identity
ā [] == [] is True but [] is [] is False!
1ļøā£4ļøā£ Exception handling?
ā try / except / else / finally
ā Always catch specific exceptions first
1ļøā£5ļøā£ @staticmethod vs @classmethod?
ā @staticmethod: no self or cls ā utility method
ā @classmethod: gets class as first arg (cls)
āāāāāāāāāāāāāāāāāāāāāā
š„ BONUS Interview Tips:
ā Always explain with a real-world example
ā Say 'I used this in my project' ā instant +1!
ā Mention time/space complexity when possible
ā If unsure ā explain what you DO know confidently
š Get Python Projects with Source Code:
š https://t.me/Projectwithsourcecodes
š¢ Save this post + Share with your batch!
#PythonInterview #InterviewQuestions #Python2026
#TCSInterview #InfosysInterview #PlacementPrep
#Freshers2026 #CodingInterview #BTech #MCA #BCA
#PythonDeveloper #TechInterview #ProjectWithSourceCodes
#StudentsOfIndia #CampusPlacement #OffCampus
(TCS ⢠Infosys ⢠Wipro ⢠Startups ā ye sab poochte hain!)
Save karo ā interview se pehle zaroor padho! š
āāāāāāāāāāāāāāāāāāāāāā
BASICS (Freshers ke liye must!)
1ļøā£ List vs Tuple?
ā List = mutable | Tuple = immutable
ā Tuple is faster & used for fixed data
2ļøā£ What are Python decorators?
ā Functions jo dusre functions wrap karte hain
ā @staticmethod, @classmethod, @property
ā Flask mein @app.route bhi ek decorator hai
3ļøā£ deepcopy vs shallow copy?
ā Shallow = reference copy (nested objects share)
ā Deep = completely new independent copy
ā import copy ā copy.deepcopy(obj)
4ļøā£ What is GIL in Python?
ā Global Interpreter Lock
ā Only ONE thread runs at a time in CPython
ā Use multiprocessing for true parallelism
5ļøā£ What are generators?
ā Use yield instead of return
ā Memory efficient ā values on demand
ā Perfect for large datasets
āāāāāāāāāāāāāāāāāāāāāā
INTERMEDIATE (Most asked in tech rounds!)
6ļøā£ List comprehension vs map() ā which is faster?
ā List comprehension is more readable & Pythonic
ā map() slightly faster for simple functions
7ļøā£ What is *args and **kwargs?
ā *args = variable positional arguments
ā **kwargs = variable keyword arguments
8ļøā£ Mutable vs Immutable data types?
ā Mutable: list, dict, set
ā Immutable: int, str, tuple, float
9ļøā£ What is __init__ vs __new__?
ā __new__ creates the object
ā __init__ initializes it (constructor)
š Python memory management?
ā Reference counting + Garbage collector
ā del keyword decrements reference count
āāāāāāāāāāāāāāāāāāāāāā
ADVANCED (For senior/experienced roles!)
1ļøā£1ļøā£ Lambda function?
ā Anonymous one-line function
ā square = lambda x: x**2
1ļøā£2ļøā£ OOPS in Python?
ā Class, Object, Inheritance, Polymorphism
ā Always give a real example (Bank, Car etc.)
1ļøā£3ļøā£ is vs == difference?
ā == checks value | is checks memory identity
ā [] == [] is True but [] is [] is False!
1ļøā£4ļøā£ Exception handling?
ā try / except / else / finally
ā Always catch specific exceptions first
1ļøā£5ļøā£ @staticmethod vs @classmethod?
ā @staticmethod: no self or cls ā utility method
ā @classmethod: gets class as first arg (cls)
āāāāāāāāāāāāāāāāāāāāāā
š„ BONUS Interview Tips:
ā Always explain with a real-world example
ā Say 'I used this in my project' ā instant +1!
ā Mention time/space complexity when possible
ā If unsure ā explain what you DO know confidently
š Get Python Projects with Source Code:
š https://t.me/Projectwithsourcecodes
š¢ Save this post + Share with your batch!
#PythonInterview #InterviewQuestions #Python2026
#TCSInterview #InfosysInterview #PlacementPrep
#Freshers2026 #CodingInterview #BTech #MCA #BCA
#PythonDeveloper #TechInterview #ProjectWithSourceCodes
#StudentsOfIndia #CampusPlacement #OffCampus
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
ā” 20 Git & GitHub Commands Every Developer
MUST Know in 2026!
Interview mein Git poochha aur answer nahi aaya
= instant reject! š¬ Save this NOW! š
āāāāāāāāāāāāāāāāāāāāāā
šµ BASICS ā Start Here
1. git init
ā New repo start karo local folder mein
2. git clone <url>
ā GitHub se project download karo
3. git status
ā Kaunsi files changed hain dekho
4. git add .
ā Sari files staging mein add karo
5. git commit -m 'your message'
ā Changes save karo with a message
6. git push origin main
ā Code GitHub pe upload karo
7. git pull origin main
ā GitHub se latest code download karo
āāāāāāāāāāāāāāāāāāāāāā
š¢ BRANCHING ā Team Projects ke liye MUST!
8. git branch feature-login
ā New branch banao
9. git checkout feature-login
ā Us branch pe switch karo
10. git checkout -b feature-login
ā Branch banao + switch ā ek command mein!
11. git merge feature-login
ā Branch ka code main mein merge karo
12. git branch -d feature-login
ā Kaam khatam? Branch delete karo
āāāāāāāāāāāāāāāāāāāāāā
š” HISTORY & FIXES ā Ghabrao mat!
13. git log --oneline
ā Short commit history dekho
14. git diff
ā Exactly kya change hua dekho
15. git stash
ā Changes temporarily save karo
(Branch switch karne se pehle!)
16. git stash pop
ā Stash kiya hua code wapas lao
17. git reset --soft HEAD~1
ā Last commit undo karo (code safe)
18. git revert <commit-id>
ā Specific commit ko reverse karo
āāāāāāāāāāāāāāāāāāāāāā
š“ PRO TRICKS ā Impress Everyone!
19. git log --graph --all --oneline
ā Beautiful visual branch history!
(Interviewers love when you know this)
20. git shortlog -sn
ā Team mein kisne kitna contribute kiya
āāāāāāāāāāāāāāāāāāāāāā
š” BONUS ā GitHub Profile Tips:
ā Minimum 3 pinned repositories
ā Every repo needs a good README.md
ā Add screenshots in README (huge impact!)
ā Commit daily ā green squares matter!
ā Star + fork popular repos in your domain
ā Add profile README (github.com/username)
šÆ Interview Git Questions:
Q: What is git rebase vs merge?
ā Merge creates a new commit combining branches
ā Rebase moves commits on top of another branch
ā Rebase = cleaner history
Q: How to resolve merge conflicts?
ā git status to see conflicted files
ā Open file ā choose which code to keep
ā git add . ā git commit
Q: git fetch vs git pull?
ā fetch = download but DON'T merge
ā pull = download + merge automatically
āāāāāāāāāāāāāāāāāāāāāā
š Add your projects on GitHub from here:
š https://t.me/Projectwithsourcecodes
š¬ Save this post ā you WILL need it! š
š¢ Share with your batch ā
Git interview mein sabko help milegi! š
#Git #GitHub #GitCommands #GitTips
#VersionControl #DeveloperTools #PlacementPrep
#CodingTips #BTech #MCA #BCA #Freshers2026
#GitHubProfile #OpenSource #TechInterview
#ProjectWithSourceCodes #StudentsOfIndia
#SoftwareEngineering #CodingCommunity
MUST Know in 2026!
Interview mein Git poochha aur answer nahi aaya
= instant reject! š¬ Save this NOW! š
āāāāāāāāāāāāāāāāāāāāāā
šµ BASICS ā Start Here
1. git init
ā New repo start karo local folder mein
2. git clone <url>
ā GitHub se project download karo
3. git status
ā Kaunsi files changed hain dekho
4. git add .
ā Sari files staging mein add karo
5. git commit -m 'your message'
ā Changes save karo with a message
6. git push origin main
ā Code GitHub pe upload karo
7. git pull origin main
ā GitHub se latest code download karo
āāāāāāāāāāāāāāāāāāāāāā
š¢ BRANCHING ā Team Projects ke liye MUST!
8. git branch feature-login
ā New branch banao
9. git checkout feature-login
ā Us branch pe switch karo
10. git checkout -b feature-login
ā Branch banao + switch ā ek command mein!
11. git merge feature-login
ā Branch ka code main mein merge karo
12. git branch -d feature-login
ā Kaam khatam? Branch delete karo
āāāāāāāāāāāāāāāāāāāāāā
š” HISTORY & FIXES ā Ghabrao mat!
13. git log --oneline
ā Short commit history dekho
14. git diff
ā Exactly kya change hua dekho
15. git stash
ā Changes temporarily save karo
(Branch switch karne se pehle!)
16. git stash pop
ā Stash kiya hua code wapas lao
17. git reset --soft HEAD~1
ā Last commit undo karo (code safe)
18. git revert <commit-id>
ā Specific commit ko reverse karo
āāāāāāāāāāāāāāāāāāāāāā
š“ PRO TRICKS ā Impress Everyone!
19. git log --graph --all --oneline
ā Beautiful visual branch history!
(Interviewers love when you know this)
20. git shortlog -sn
ā Team mein kisne kitna contribute kiya
āāāāāāāāāāāāāāāāāāāāāā
š” BONUS ā GitHub Profile Tips:
ā Minimum 3 pinned repositories
ā Every repo needs a good README.md
ā Add screenshots in README (huge impact!)
ā Commit daily ā green squares matter!
ā Star + fork popular repos in your domain
ā Add profile README (github.com/username)
šÆ Interview Git Questions:
Q: What is git rebase vs merge?
ā Merge creates a new commit combining branches
ā Rebase moves commits on top of another branch
ā Rebase = cleaner history
Q: How to resolve merge conflicts?
ā git status to see conflicted files
ā Open file ā choose which code to keep
ā git add . ā git commit
Q: git fetch vs git pull?
ā fetch = download but DON'T merge
ā pull = download + merge automatically
āāāāāāāāāāāāāāāāāāāāāā
š Add your projects on GitHub from here:
š https://t.me/Projectwithsourcecodes
š¬ Save this post ā you WILL need it! š
š¢ Share with your batch ā
Git interview mein sabko help milegi! š
#Git #GitHub #GitCommands #GitTips
#VersionControl #DeveloperTools #PlacementPrep
#CodingTips #BTech #MCA #BCA #Freshers2026
#GitHubProfile #OpenSource #TechInterview
#ProjectWithSourceCodes #StudentsOfIndia
#SoftwareEngineering #CodingCommunity
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
INTERVIEW PREP 2026 ā Most Asked Questions!
Asked in TCS, Infosys, Wipro, Accenture & Startups
====================================
JAVA / OOP QUESTIONS
Q1: What is the difference between Abstract Class and Interface?
ANS: Abstract class can have method body + constructor.
Interface has only abstract methods (before Java 8).
Use abstract class for IS-A, interface for CAN-DO.
Q2: What is method overloading vs overriding?
ANS: Overloading = same method name, different params (compile time)
Overriding = child class redefines parent method (runtime)
Q3: What is a NullPointerException? How to avoid it?
ANS: Accessing object/method on null reference.
Fix: Use Optional<>, null checks, or @NotNull annotation.
====================================
DATABASE (SQL) QUESTIONS
Q4: Difference between WHERE and HAVING?
ANS: WHERE filters rows BEFORE grouping.
HAVING filters groups AFTER GROUP BY.
WHERE cannot use aggregate functions. HAVING can.
Q5: What are ACID properties?
ANS: A - Atomicity (all or nothing)
C - Consistency (valid state always)
I - Isolation (transactions don't interfere)
D - Durability (committed = permanent)
Q6: What is the difference between INNER JOIN and LEFT JOIN?
ANS: INNER JOIN = only matching rows from both tables
LEFT JOIN = all rows from left + matching from right
====================================
HR ROUND QUESTIONS
Q7: Tell me about yourself?
FORMULA: Name + Degree + Skills + Project + Goal
EXAMPLE: 'I am [Name], pursuing BCA final year.
I am skilled in Java, React and SQL.
I built a Student Management System using Spring Boot.
I am looking to join a company where I can grow as
a full stack developer.'
Q8: Why should we hire you?
TIP: Mention 1 specific skill + 1 project + 1 soft skill
'I know React + Node JS, I have built 3 live projects,
and I learn fast and work well in teams.'
Q9: What is your biggest weakness?
SMART ANSWER: Turn it into a strength!
'I used to spend too much time perfecting code.
Now I set time limits and focus on working solutions first.'
====================================
BONUS TIPS TO CRACK TECH INTERVIEWS
-> Practice 2 LeetCode Easy problems daily
-> Revise OOPS concepts every week
-> Always explain your thinking out loud
-> Have 2-3 projects ready to explain in detail
-> Ask 1 smart question at the end of interview
-> Dress formally even for online interviews!
====================================
Want FREE projects to show in your interview?
Get full source code here:
https://t.me/Projectwithsourcecodes
Save this post for your interview prep!
Share with your friends appearing for placements!
#InterviewTips #PlacementPrep #TCS #Infosys #Wipro
#Accenture #JavaInterview #SQLInterview #HRInterview
#BTech2026 #MCA2026 #BCA2026 #CampusPlacement
#OffCampus #TechInterview #OOPs #ProjectWithSourceCodes
#StudentsOfIndia #FreshersJobs #InterviewQuestions
Asked in TCS, Infosys, Wipro, Accenture & Startups
====================================
JAVA / OOP QUESTIONS
Q1: What is the difference between Abstract Class and Interface?
ANS: Abstract class can have method body + constructor.
Interface has only abstract methods (before Java 8).
Use abstract class for IS-A, interface for CAN-DO.
Q2: What is method overloading vs overriding?
ANS: Overloading = same method name, different params (compile time)
Overriding = child class redefines parent method (runtime)
Q3: What is a NullPointerException? How to avoid it?
ANS: Accessing object/method on null reference.
Fix: Use Optional<>, null checks, or @NotNull annotation.
====================================
DATABASE (SQL) QUESTIONS
Q4: Difference between WHERE and HAVING?
ANS: WHERE filters rows BEFORE grouping.
HAVING filters groups AFTER GROUP BY.
WHERE cannot use aggregate functions. HAVING can.
Q5: What are ACID properties?
ANS: A - Atomicity (all or nothing)
C - Consistency (valid state always)
I - Isolation (transactions don't interfere)
D - Durability (committed = permanent)
Q6: What is the difference between INNER JOIN and LEFT JOIN?
ANS: INNER JOIN = only matching rows from both tables
LEFT JOIN = all rows from left + matching from right
====================================
HR ROUND QUESTIONS
Q7: Tell me about yourself?
FORMULA: Name + Degree + Skills + Project + Goal
EXAMPLE: 'I am [Name], pursuing BCA final year.
I am skilled in Java, React and SQL.
I built a Student Management System using Spring Boot.
I am looking to join a company where I can grow as
a full stack developer.'
Q8: Why should we hire you?
TIP: Mention 1 specific skill + 1 project + 1 soft skill
'I know React + Node JS, I have built 3 live projects,
and I learn fast and work well in teams.'
Q9: What is your biggest weakness?
SMART ANSWER: Turn it into a strength!
'I used to spend too much time perfecting code.
Now I set time limits and focus on working solutions first.'
====================================
BONUS TIPS TO CRACK TECH INTERVIEWS
-> Practice 2 LeetCode Easy problems daily
-> Revise OOPS concepts every week
-> Always explain your thinking out loud
-> Have 2-3 projects ready to explain in detail
-> Ask 1 smart question at the end of interview
-> Dress formally even for online interviews!
====================================
Want FREE projects to show in your interview?
Get full source code here:
https://t.me/Projectwithsourcecodes
Save this post for your interview prep!
Share with your friends appearing for placements!
#InterviewTips #PlacementPrep #TCS #Infosys #Wipro
#Accenture #JavaInterview #SQLInterview #HRInterview
#BTech2026 #MCA2026 #BCA2026 #CampusPlacement
#OffCampus #TechInterview #OOPs #ProjectWithSourceCodes
#StudentsOfIndia #FreshersJobs #InterviewQuestions
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
SYSTEM DESIGN BASICS ā Save This Post!
Asked in Amazon Microsoft Walmart Interviews!
====================================
System Design separates freshers from
SDE-2 level thinkers. Learn the basics NOW
to stand out in interviews!
====================================
CONCEPT 1: SCALABILITY
What it means: System handles MORE users
without breaking down.
Two types:
Vertical Scaling -> Add more power to 1 server
Horizontal Scaling -> Add MORE servers
Real example: Instagram uses horizontal scaling
with 1000s of servers worldwide!
====================================
CONCEPT 2: LOAD BALANCER
What it means: Distributes traffic across
multiple servers so no single server overloads.
Real example: When you open Amazon.com,
a load balancer sends you to the LEAST busy
server among 1000s of available servers!
Tools: Nginx, AWS ELB, HAProxy
====================================
CONCEPT 3: CACHING
What it means: Store frequently used data
in fast memory to avoid repeated DB calls.
Real example: Twitter caches trending tweets
so millions can see them WITHOUT hitting
the database every single time!
Tools: Redis, Memcached
====================================
CONCEPT 4: DATABASE SHARDING
What it means: Split ONE huge database into
smaller pieces (shards) across servers.
Real example: WhatsApp shards user data by
phone number ranges across different servers!
Why: 1 server CANNOT store billions of users!
====================================
CONCEPT 5: MICROSERVICES
What it means: Break ONE big application into
small independent services.
Real example: Amazon has separate services for
Cart, Payment, Inventory, Shipping ā all talking
to each other via APIs!
Why: Easy to scale + update individual parts
without breaking the whole system!
====================================
CONCEPT 6: CDN (Content Delivery Network)
What it means: Store copies of content (images,
videos) on servers CLOSE to the user's location.
Real example: YouTube video loads fast in India
because CDN servers exist IN India, not just US!
Tools: Cloudflare, AWS CloudFront
====================================
CONCEPT 7: MESSAGE QUEUES
What it means: Tasks wait in a queue and get
processed one by one, even under heavy load.
Real example: When you order food on Swiggy,
your order goes into a queue before being
assigned to a delivery partner!
Tools: Kafka, RabbitMQ, AWS SQS
====================================
HOW TO ANSWER SYSTEM DESIGN IN INTERVIEW:
Step 1: Clarify requirements (ask questions!)
Step 2: Estimate scale (users, requests/sec)
Step 3: Draw high-level architecture
Step 4: Discuss database design
Step 5: Discuss scaling + caching strategy
Step 6: Discuss trade-offs
Even freshers get asked 'Design a URL shortener'
or 'Design Instagram' in interviews now!
====================================
FREE RESOURCES TO LEARN MORE:
'System Design Primer' on GitHub (FREE)
ByteByteGo YouTube channel
Gaurav Sen YouTube channel (Hindi/English)
====================================
Build a project using these concepts!
Get FREE source codes:
https://t.me/Projectwithsourcecodes
Save this post for interview prep!
#SystemDesign #SystemDesignInterview #Scalability
#LoadBalancer #Caching #Microservices #Redis
#Kafka #CDN #BTech2026 #MCA2026 #BCA2026
#PlacementPrep #Amazon #Microsoft #Walmart
#SDE #TechInterview #ProjectWithSourceCodes
#StudentsOfIndia #SystemDesignBasics
Asked in Amazon Microsoft Walmart Interviews!
====================================
System Design separates freshers from
SDE-2 level thinkers. Learn the basics NOW
to stand out in interviews!
====================================
CONCEPT 1: SCALABILITY
What it means: System handles MORE users
without breaking down.
Two types:
Vertical Scaling -> Add more power to 1 server
Horizontal Scaling -> Add MORE servers
Real example: Instagram uses horizontal scaling
with 1000s of servers worldwide!
====================================
CONCEPT 2: LOAD BALANCER
What it means: Distributes traffic across
multiple servers so no single server overloads.
Real example: When you open Amazon.com,
a load balancer sends you to the LEAST busy
server among 1000s of available servers!
Tools: Nginx, AWS ELB, HAProxy
====================================
CONCEPT 3: CACHING
What it means: Store frequently used data
in fast memory to avoid repeated DB calls.
Real example: Twitter caches trending tweets
so millions can see them WITHOUT hitting
the database every single time!
Tools: Redis, Memcached
====================================
CONCEPT 4: DATABASE SHARDING
What it means: Split ONE huge database into
smaller pieces (shards) across servers.
Real example: WhatsApp shards user data by
phone number ranges across different servers!
Why: 1 server CANNOT store billions of users!
====================================
CONCEPT 5: MICROSERVICES
What it means: Break ONE big application into
small independent services.
Real example: Amazon has separate services for
Cart, Payment, Inventory, Shipping ā all talking
to each other via APIs!
Why: Easy to scale + update individual parts
without breaking the whole system!
====================================
CONCEPT 6: CDN (Content Delivery Network)
What it means: Store copies of content (images,
videos) on servers CLOSE to the user's location.
Real example: YouTube video loads fast in India
because CDN servers exist IN India, not just US!
Tools: Cloudflare, AWS CloudFront
====================================
CONCEPT 7: MESSAGE QUEUES
What it means: Tasks wait in a queue and get
processed one by one, even under heavy load.
Real example: When you order food on Swiggy,
your order goes into a queue before being
assigned to a delivery partner!
Tools: Kafka, RabbitMQ, AWS SQS
====================================
HOW TO ANSWER SYSTEM DESIGN IN INTERVIEW:
Step 1: Clarify requirements (ask questions!)
Step 2: Estimate scale (users, requests/sec)
Step 3: Draw high-level architecture
Step 4: Discuss database design
Step 5: Discuss scaling + caching strategy
Step 6: Discuss trade-offs
Even freshers get asked 'Design a URL shortener'
or 'Design Instagram' in interviews now!
====================================
FREE RESOURCES TO LEARN MORE:
'System Design Primer' on GitHub (FREE)
ByteByteGo YouTube channel
Gaurav Sen YouTube channel (Hindi/English)
====================================
Build a project using these concepts!
Get FREE source codes:
https://t.me/Projectwithsourcecodes
Save this post for interview prep!
#SystemDesign #SystemDesignInterview #Scalability
#LoadBalancer #Caching #Microservices #Redis
#Kafka #CDN #BTech2026 #MCA2026 #BCA2026
#PlacementPrep #Amazon #Microsoft #Walmart
#SDE #TechInterview #ProjectWithSourceCodes
#StudentsOfIndia #SystemDesignBasics
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
SQL CHEAT SHEET ā Save This Post!
Most Asked Queries in Tech Interviews!
====================================
SQL is asked in 90% of tech interviews ā
TCS, Infosys, Amazon, even AI roles need it!
Master these queries TODAY!
====================================
BASIC QUERIES
SELECT * FROM employees;
-> Get all data from table
SELECT name, salary FROM employees
WHERE salary > 50000;
-> Filter rows with condition
SELECT * FROM employees
ORDER BY salary DESC LIMIT 5;
-> Top 5 highest paid employees
====================================
AGGREGATE FUNCTIONS
SELECT COUNT(*) FROM employees;
-> Total number of rows
SELECT AVG(salary) FROM employees;
-> Average salary
SELECT department, COUNT(*) FROM employees
GROUP BY department;
-> Count employees per department
SELECT department, AVG(salary) FROM employees
GROUP BY department
HAVING AVG(salary) > 60000;
-> Departments with avg salary > 60k
====================================
JOINS ā Most Asked in Interviews!
INNER JOIN -> Only matching rows in both tables
SELECT e.name, d.dept_name
FROM employees e
INNER JOIN departments d
ON e.dept_id = d.id;
LEFT JOIN -> All rows from left + matching right
SELECT e.name, d.dept_name
FROM employees e
LEFT JOIN departments d
ON e.dept_id = d.id;
SELF JOIN -> Table joined with itself
SELECT e1.name, e2.name AS manager
FROM employees e1
JOIN employees e2
ON e1.manager_id = e2.id;
====================================
SUBQUERIES ā Asked in Advanced Rounds!
Find employees earning more than average:
SELECT name FROM employees
WHERE salary > (
SELECT AVG(salary) FROM employees
);
Find 2nd highest salary (Classic Question!):
SELECT MAX(salary) FROM employees
WHERE salary < (
SELECT MAX(salary) FROM employees
);
====================================
WINDOW FUNCTIONS ā Modern SQL!
Rank employees by salary:
SELECT name, salary,
RANK() OVER (ORDER BY salary DESC) as rnk
FROM employees;
Running total of salaries:
SELECT name, salary,
SUM(salary) OVER (ORDER BY id) as running_total
FROM employees;
====================================
MUST-KNOW CONCEPTS:
Primary Key -> Unique identifier for each row
Foreign Key -> Links 2 tables together
Index -> Speeds up search queries
Normalization -> Reduce data redundancy
Transaction -> ACID properties (all or nothing)
====================================
TOP 5 SQL INTERVIEW QUESTIONS:
1. Find duplicate records in a table
2. Find employees with no manager
3. Find departments with zero employees
4. Find Nth highest salary
5. Find employees who joined this month
Practice these on a free SQL site!
====================================
PRACTICE FREE ON:
SQLZoo.net
HackerRank SQL section
LeetCode Database problems
====================================
Save this post before your next interview!
Get FREE projects too:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SQLCheatSheet #SQL #DatabaseInterview #MySQL
#PostgreSQL #JoinsInSQL #Subqueries #WindowFunctions
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#TechInterview #DataAnalyst #BackendDeveloper
#ProjectWithSourceCodes #StudentsOfIndia #LearnSQL
Most Asked Queries in Tech Interviews!
====================================
SQL is asked in 90% of tech interviews ā
TCS, Infosys, Amazon, even AI roles need it!
Master these queries TODAY!
====================================
BASIC QUERIES
SELECT * FROM employees;
-> Get all data from table
SELECT name, salary FROM employees
WHERE salary > 50000;
-> Filter rows with condition
SELECT * FROM employees
ORDER BY salary DESC LIMIT 5;
-> Top 5 highest paid employees
====================================
AGGREGATE FUNCTIONS
SELECT COUNT(*) FROM employees;
-> Total number of rows
SELECT AVG(salary) FROM employees;
-> Average salary
SELECT department, COUNT(*) FROM employees
GROUP BY department;
-> Count employees per department
SELECT department, AVG(salary) FROM employees
GROUP BY department
HAVING AVG(salary) > 60000;
-> Departments with avg salary > 60k
====================================
JOINS ā Most Asked in Interviews!
INNER JOIN -> Only matching rows in both tables
SELECT e.name, d.dept_name
FROM employees e
INNER JOIN departments d
ON e.dept_id = d.id;
LEFT JOIN -> All rows from left + matching right
SELECT e.name, d.dept_name
FROM employees e
LEFT JOIN departments d
ON e.dept_id = d.id;
SELF JOIN -> Table joined with itself
SELECT e1.name, e2.name AS manager
FROM employees e1
JOIN employees e2
ON e1.manager_id = e2.id;
====================================
SUBQUERIES ā Asked in Advanced Rounds!
Find employees earning more than average:
SELECT name FROM employees
WHERE salary > (
SELECT AVG(salary) FROM employees
);
Find 2nd highest salary (Classic Question!):
SELECT MAX(salary) FROM employees
WHERE salary < (
SELECT MAX(salary) FROM employees
);
====================================
WINDOW FUNCTIONS ā Modern SQL!
Rank employees by salary:
SELECT name, salary,
RANK() OVER (ORDER BY salary DESC) as rnk
FROM employees;
Running total of salaries:
SELECT name, salary,
SUM(salary) OVER (ORDER BY id) as running_total
FROM employees;
====================================
MUST-KNOW CONCEPTS:
Primary Key -> Unique identifier for each row
Foreign Key -> Links 2 tables together
Index -> Speeds up search queries
Normalization -> Reduce data redundancy
Transaction -> ACID properties (all or nothing)
====================================
TOP 5 SQL INTERVIEW QUESTIONS:
1. Find duplicate records in a table
2. Find employees with no manager
3. Find departments with zero employees
4. Find Nth highest salary
5. Find employees who joined this month
Practice these on a free SQL site!
====================================
PRACTICE FREE ON:
SQLZoo.net
HackerRank SQL section
LeetCode Database problems
====================================
Save this post before your next interview!
Get FREE projects too:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SQLCheatSheet #SQL #DatabaseInterview #MySQL
#PostgreSQL #JoinsInSQL #Subqueries #WindowFunctions
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#TechInterview #DataAnalyst #BackendDeveloper
#ProjectWithSourceCodes #StudentsOfIndia #LearnSQL
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
PYTHON CHEAT SHEET ā Save This!
Most Asked Python in Tech Interviews!
====================================
Python is #1 language for AI, Data Science,
Backend & Automation roles. Master this!
====================================
DATA TYPES & BASICS
x = 10 # int
y = 3.14 # float
s = 'hello' # string
b = True # boolean
l = [1,2,3] # list (mutable)
t = (1,2,3) # tuple (immutable)
d = {'a': 1} # dictionary
st = {1,2,3} # set (unique values)
====================================
STRINGS ā Most Asked!
s = 'Hello World'
s.upper() # 'HELLO WORLD'
s.lower() # 'hello world'
s.split(' ') # ['Hello', 'World']
s.replace('o','0') # 'Hell0 W0rld'
s.strip() # remove whitespace
len(s) # 11
s[0:5] # 'Hello' (slicing)
s[::-1] # reverse string!
f'Name: {s}' # f-string formatting
====================================
LIST OPERATIONS
l = [3, 1, 4, 1, 5]
l.append(9) # add to end
l.insert(0, 7) # insert at index 0
l.remove(1) # remove first '1'
l.pop() # remove last element
l.sort() # sort in place
sorted(l) # returns new sorted list
l.reverse() # reverse in place
len(l) # length of list
sum(l) # sum of all elements
max(l), min(l) # max and min value
====================================
LIST COMPREHENSION ā Interviewers Love!
squares = [x**2 for x in range(10)]
# [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
evens = [x for x in range(20) if x%2==0]
# [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
====================================
DICTIONARY TRICKS
d = {'name': 'Rahul', 'age': 22}
d['name'] # 'Rahul'
d.get('city', 'N/A') # safe get
d.keys() # all keys
d.values() # all values
d.items() # key-value pairs
d.update({'city': 'Delhi'}) # add/update
====================================
FUNCTIONS & LAMBDA
def add(a, b):
return a + b
# Lambda (one-line function)
square = lambda x: x**2
square(5) # 25
# *args and **kwargs
def greet(*names):
for name in names:
print(f'Hi {name}')
====================================
MUST-KNOW PYTHON CONCEPTS:
List vs Tuple -> mutable vs immutable
Deep vs Shallow copy -> copy.deepcopy()
Global vs Local -> variable scope
try/except -> error handling
with open() -> file handling
OOP: class, __init__, self, inheritance
====================================
TOP 5 PYTHON INTERVIEW QUESTIONS:
1. Difference: list vs tuple vs set vs dict?
2. What is a lambda function?
3. How does Python handle memory management?
4. What are decorators in Python?
5. Difference: deep copy vs shallow copy?
====================================
PRACTICE FREE ON:
HackerRank -> hackerrank.com/domains/python
LeetCode -> leetcode.com
W3Schools -> w3schools.com/python
====================================
Save this before your next interview!
Get FREE Python projects with source code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#PythonCheatSheet #Python #PythonInterview
#DataScience #MachineLearning #PythonDeveloper
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#CodingInterview #TechInterview #LearnPython
#ProjectWithSourceCodes #StudentsOfIndia
Most Asked Python in Tech Interviews!
====================================
Python is #1 language for AI, Data Science,
Backend & Automation roles. Master this!
====================================
DATA TYPES & BASICS
x = 10 # int
y = 3.14 # float
s = 'hello' # string
b = True # boolean
l = [1,2,3] # list (mutable)
t = (1,2,3) # tuple (immutable)
d = {'a': 1} # dictionary
st = {1,2,3} # set (unique values)
====================================
STRINGS ā Most Asked!
s = 'Hello World'
s.upper() # 'HELLO WORLD'
s.lower() # 'hello world'
s.split(' ') # ['Hello', 'World']
s.replace('o','0') # 'Hell0 W0rld'
s.strip() # remove whitespace
len(s) # 11
s[0:5] # 'Hello' (slicing)
s[::-1] # reverse string!
f'Name: {s}' # f-string formatting
====================================
LIST OPERATIONS
l = [3, 1, 4, 1, 5]
l.append(9) # add to end
l.insert(0, 7) # insert at index 0
l.remove(1) # remove first '1'
l.pop() # remove last element
l.sort() # sort in place
sorted(l) # returns new sorted list
l.reverse() # reverse in place
len(l) # length of list
sum(l) # sum of all elements
max(l), min(l) # max and min value
====================================
LIST COMPREHENSION ā Interviewers Love!
squares = [x**2 for x in range(10)]
# [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
evens = [x for x in range(20) if x%2==0]
# [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
====================================
DICTIONARY TRICKS
d = {'name': 'Rahul', 'age': 22}
d['name'] # 'Rahul'
d.get('city', 'N/A') # safe get
d.keys() # all keys
d.values() # all values
d.items() # key-value pairs
d.update({'city': 'Delhi'}) # add/update
====================================
FUNCTIONS & LAMBDA
def add(a, b):
return a + b
# Lambda (one-line function)
square = lambda x: x**2
square(5) # 25
# *args and **kwargs
def greet(*names):
for name in names:
print(f'Hi {name}')
====================================
MUST-KNOW PYTHON CONCEPTS:
List vs Tuple -> mutable vs immutable
Deep vs Shallow copy -> copy.deepcopy()
Global vs Local -> variable scope
try/except -> error handling
with open() -> file handling
OOP: class, __init__, self, inheritance
====================================
TOP 5 PYTHON INTERVIEW QUESTIONS:
1. Difference: list vs tuple vs set vs dict?
2. What is a lambda function?
3. How does Python handle memory management?
4. What are decorators in Python?
5. Difference: deep copy vs shallow copy?
====================================
PRACTICE FREE ON:
HackerRank -> hackerrank.com/domains/python
LeetCode -> leetcode.com
W3Schools -> w3schools.com/python
====================================
Save this before your next interview!
Get FREE Python projects with source code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#PythonCheatSheet #Python #PythonInterview
#DataScience #MachineLearning #PythonDeveloper
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#CodingInterview #TechInterview #LearnPython
#ProjectWithSourceCodes #StudentsOfIndia
HackerRank
Solve Programming Questions | HackerRank
A step by step guide to Python, a language that is easy to pick up yet one of the most powerful.
DSA CHEAT SHEET ā Save This!
Data Structures Asked in Every Interview!
====================================
DSA is tested in ALL product company interviews!
Amazon, Google, Microsoft, Flipkart, Adobe ā
ALL start with DSA rounds. Master this!
====================================
ARRAYS ā Most Basic, Most Asked!
Find max/min in array -> O(n) linear scan
Reverse an array -> two pointer approach
Find duplicates -> use HashSet O(n)
Rotate array by k -> reverse technique
Two Sum problem -> HashMap O(n)
Sliding Window -> for subarray problems
====================================
STRINGS
Palindrome check -> two pointers
Anagram check -> sort both or HashMap
Longest common prefix -> vertical scan
Count vowels/consonants -> loop + set
String reversal -> s[::-1] in Python
====================================
LINKED LIST ā Very Frequently Asked!
Reverse a linked list -> 3 pointer trick
Detect cycle -> Floyd's algo (slow/fast)
Find middle node -> slow/fast pointers
Merge 2 sorted lists -> compare & merge
Remove Nth node from end -> two pass
====================================
STACK & QUEUE
Stack: LIFO ā use for:
-> Valid parentheses check
-> Next Greater Element
-> Undo/Redo operations
Queue: FIFO ā use for:
-> BFS (level order traversal)
-> Sliding window maximum
====================================
TREES ā 30% of Interview Questions!
Inorder: Left -> Root -> Right
Preorder: Root -> Left -> Right
Postorder: Left -> Right -> Root
Level Order -> use Queue (BFS)
Height of tree -> recursion
Check BST -> inorder should be sorted
LCA of two nodes -> recursive approach
====================================
SORTING ALGORITHMS
Bubble Sort -> O(n²) | Simple
Selection Sort -> O(n²) | Simple
Insertion Sort -> O(n²) | Best for small
Merge Sort -> O(nlogn) | Stable sort
Quick Sort -> O(nlogn) | In-place
For interviews: Know Merge Sort well!
====================================
SEARCHING
Linear Search -> O(n) | Unsorted array
Binary Search -> O(logn) | Sorted array only
Binary Search template:
low, high = 0, len(arr)-1
while low <= high:
mid = (low + high) // 2
if arr[mid] == target: return mid
elif arr[mid] < target: low = mid+1
else: high = mid-1
====================================
TIME COMPLEXITY QUICK REFERENCE:
O(1) -> Constant | Array index access
O(logn) -> Log | Binary search
O(n) -> Linear | Single loop
O(nlogn) -> Linearithmic | Merge sort
O(n²) -> Quadratic | Nested loops
====================================
TOP DSA PLATFORMS TO PRACTICE:
LeetCode -> leetcode.com (must!)
HackerRank -> hackerrank.com
GeeksForGeeks -> geeksforgeeks.org
Codeforces -> codeforces.com
====================================
Save this post ā revise before every interview!
Get FREE projects with DSA implementation:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#DSA #DataStructures #Algorithms #LeetCode
#CodingInterview #TechInterview #Placements
#BTech2026 #MCA2026 #BCA2026 #CompetitiveCoding
#Java #Python #DSACheatSheet #FAANG
#ProjectWithSourceCodes #StudentsOfIndia
Data Structures Asked in Every Interview!
====================================
DSA is tested in ALL product company interviews!
Amazon, Google, Microsoft, Flipkart, Adobe ā
ALL start with DSA rounds. Master this!
====================================
ARRAYS ā Most Basic, Most Asked!
Find max/min in array -> O(n) linear scan
Reverse an array -> two pointer approach
Find duplicates -> use HashSet O(n)
Rotate array by k -> reverse technique
Two Sum problem -> HashMap O(n)
Sliding Window -> for subarray problems
====================================
STRINGS
Palindrome check -> two pointers
Anagram check -> sort both or HashMap
Longest common prefix -> vertical scan
Count vowels/consonants -> loop + set
String reversal -> s[::-1] in Python
====================================
LINKED LIST ā Very Frequently Asked!
Reverse a linked list -> 3 pointer trick
Detect cycle -> Floyd's algo (slow/fast)
Find middle node -> slow/fast pointers
Merge 2 sorted lists -> compare & merge
Remove Nth node from end -> two pass
====================================
STACK & QUEUE
Stack: LIFO ā use for:
-> Valid parentheses check
-> Next Greater Element
-> Undo/Redo operations
Queue: FIFO ā use for:
-> BFS (level order traversal)
-> Sliding window maximum
====================================
TREES ā 30% of Interview Questions!
Inorder: Left -> Root -> Right
Preorder: Root -> Left -> Right
Postorder: Left -> Right -> Root
Level Order -> use Queue (BFS)
Height of tree -> recursion
Check BST -> inorder should be sorted
LCA of two nodes -> recursive approach
====================================
SORTING ALGORITHMS
Bubble Sort -> O(n²) | Simple
Selection Sort -> O(n²) | Simple
Insertion Sort -> O(n²) | Best for small
Merge Sort -> O(nlogn) | Stable sort
Quick Sort -> O(nlogn) | In-place
For interviews: Know Merge Sort well!
====================================
SEARCHING
Linear Search -> O(n) | Unsorted array
Binary Search -> O(logn) | Sorted array only
Binary Search template:
low, high = 0, len(arr)-1
while low <= high:
mid = (low + high) // 2
if arr[mid] == target: return mid
elif arr[mid] < target: low = mid+1
else: high = mid-1
====================================
TIME COMPLEXITY QUICK REFERENCE:
O(1) -> Constant | Array index access
O(logn) -> Log | Binary search
O(n) -> Linear | Single loop
O(nlogn) -> Linearithmic | Merge sort
O(n²) -> Quadratic | Nested loops
====================================
TOP DSA PLATFORMS TO PRACTICE:
LeetCode -> leetcode.com (must!)
HackerRank -> hackerrank.com
GeeksForGeeks -> geeksforgeeks.org
Codeforces -> codeforces.com
====================================
Save this post ā revise before every interview!
Get FREE projects with DSA implementation:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#DSA #DataStructures #Algorithms #LeetCode
#CodingInterview #TechInterview #Placements
#BTech2026 #MCA2026 #BCA2026 #CompetitiveCoding
#Java #Python #DSACheatSheet #FAANG
#ProjectWithSourceCodes #StudentsOfIndia
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
DSA CHEAT SHEET - Save This!
Data Structures Asked in Every Tech Interview!
====================================
DSA is tested at Amazon, Google, Microsoft,
Flipkart, Adobe, Uber, Swiggy ā ALL of them!
Master these before your placement rounds!
====================================
ARRAYS - Most Basic, Most Asked!
Two Sum -> HashMap O(n)
Find max/min -> linear scan O(n)
Reverse array -> two pointers O(n)
Find duplicates -> HashSet O(n)
Rotate by k -> reverse technique O(n)
Subarray sum -> sliding window O(n)
Merge sorted arrays -> two pointer O(n+m)
====================================
STRINGS
Palindrome check -> two pointers O(n)
Anagram check -> sort or HashMap O(n)
Longest substring no repeat -> sliding window
String reversal -> s[::-1] in Python
Count char frequency -> HashMap O(n)
====================================
LINKED LIST - Very Frequently Asked!
Reverse linked list -> 3 pointer trick O(n)
Detect cycle -> Floyd's slow/fast O(n)
Find middle -> slow/fast pointers O(n)
Merge 2 sorted lists -> compare & link O(n)
Remove Nth from end -> two pass O(n)
====================================
STACK & QUEUE
Stack (LIFO) - use for:
-> Valid parentheses {[()]}
-> Next Greater Element
-> Undo/Redo operations
Queue (FIFO) - use for:
-> BFS (level order tree traversal)
-> Sliding window maximum
====================================
TREES - 30% of Interview Questions!
Inorder: Left Root Right
Preorder: Root Left Right
Postorder: Left Right Root
Level Order: BFS using Queue
Height of tree -> recursion O(n)
Check BST valid -> inorder sorted check
Lowest Common Ancestor -> recursive O(n)
Path sum root to leaf -> DFS O(n)
====================================
GRAPHS
BFS -> Queue, shortest path unweighted
DFS -> Stack/Recursion, path finding
Detect cycle undirected -> Union Find
Detect cycle directed -> DFS + visited
Topological Sort -> Kahn's algo (BFS)
====================================
DYNAMIC PROGRAMMING
Fibonacci -> memoization O(n)
0/1 Knapsack -> 2D DP O(n*W)
Longest Common Subsequence -> 2D DP
Coin Change -> bottom-up DP O(n*amount)
Climb Stairs -> DP same as Fibonacci
====================================
TIME COMPLEXITY QUICK REFERENCE:
O(1) Constant | Array index
O(logn) Log | Binary search
O(n) Linear | Single loop
O(nlogn) Linearithmic | Merge sort
O(n2) Quadratic | Nested loops
O(2n) Exponential | Recursion tree
====================================
TOP DSA PRACTICE PLATFORMS:
LeetCode -> leetcode.com (must!)
GeeksForGeeks -> geeksforgeeks.org
HackerRank -> hackerrank.com
Codeforces -> codeforces.com
====================================
Save this - revise before every interview!
Get FREE projects with DSA implementations:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#DSACheatSheet #DSA #DataStructures #Algorithms
#LeetCode #CodingInterview #Placements #FAANG
#BTech2026 #MCA2026 #BCA2026 #CompetitiveCoding
#Java #Python #TechInterview #DynamicProgramming
#ProjectWithSourceCodes #StudentsOfIndia
Data Structures Asked in Every Tech Interview!
====================================
DSA is tested at Amazon, Google, Microsoft,
Flipkart, Adobe, Uber, Swiggy ā ALL of them!
Master these before your placement rounds!
====================================
ARRAYS - Most Basic, Most Asked!
Two Sum -> HashMap O(n)
Find max/min -> linear scan O(n)
Reverse array -> two pointers O(n)
Find duplicates -> HashSet O(n)
Rotate by k -> reverse technique O(n)
Subarray sum -> sliding window O(n)
Merge sorted arrays -> two pointer O(n+m)
====================================
STRINGS
Palindrome check -> two pointers O(n)
Anagram check -> sort or HashMap O(n)
Longest substring no repeat -> sliding window
String reversal -> s[::-1] in Python
Count char frequency -> HashMap O(n)
====================================
LINKED LIST - Very Frequently Asked!
Reverse linked list -> 3 pointer trick O(n)
Detect cycle -> Floyd's slow/fast O(n)
Find middle -> slow/fast pointers O(n)
Merge 2 sorted lists -> compare & link O(n)
Remove Nth from end -> two pass O(n)
====================================
STACK & QUEUE
Stack (LIFO) - use for:
-> Valid parentheses {[()]}
-> Next Greater Element
-> Undo/Redo operations
Queue (FIFO) - use for:
-> BFS (level order tree traversal)
-> Sliding window maximum
====================================
TREES - 30% of Interview Questions!
Inorder: Left Root Right
Preorder: Root Left Right
Postorder: Left Right Root
Level Order: BFS using Queue
Height of tree -> recursion O(n)
Check BST valid -> inorder sorted check
Lowest Common Ancestor -> recursive O(n)
Path sum root to leaf -> DFS O(n)
====================================
GRAPHS
BFS -> Queue, shortest path unweighted
DFS -> Stack/Recursion, path finding
Detect cycle undirected -> Union Find
Detect cycle directed -> DFS + visited
Topological Sort -> Kahn's algo (BFS)
====================================
DYNAMIC PROGRAMMING
Fibonacci -> memoization O(n)
0/1 Knapsack -> 2D DP O(n*W)
Longest Common Subsequence -> 2D DP
Coin Change -> bottom-up DP O(n*amount)
Climb Stairs -> DP same as Fibonacci
====================================
TIME COMPLEXITY QUICK REFERENCE:
O(1) Constant | Array index
O(logn) Log | Binary search
O(n) Linear | Single loop
O(nlogn) Linearithmic | Merge sort
O(n2) Quadratic | Nested loops
O(2n) Exponential | Recursion tree
====================================
TOP DSA PRACTICE PLATFORMS:
LeetCode -> leetcode.com (must!)
GeeksForGeeks -> geeksforgeeks.org
HackerRank -> hackerrank.com
Codeforces -> codeforces.com
====================================
Save this - revise before every interview!
Get FREE projects with DSA implementations:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#DSACheatSheet #DSA #DataStructures #Algorithms
#LeetCode #CodingInterview #Placements #FAANG
#BTech2026 #MCA2026 #BCA2026 #CompetitiveCoding
#Java #Python #TechInterview #DynamicProgramming
#ProjectWithSourceCodes #StudentsOfIndia
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
GIT CHEAT SHEET - Save This!
Commands Every Developer Must Know!
====================================
Git is asked in EVERY tech interview!
TCS, Wipro, Infosys, startups, product cos
ALL expect you to know Git. Master these!
====================================
FIRST TIME SETUP
git config --global user.name 'Your Name'
git config --global user.email 'you@email.com'
-> Run once after installing Git
====================================
STARTING A PROJECT
git init
-> Start tracking a new project folder
git clone <url>
-> Download a repo from GitHub to your PC
====================================
DAILY COMMANDS (Use Every Day!)
git status
-> See which files changed or are new
git add .
-> Stage ALL changed files for commit
git add filename.py
-> Stage one specific file only
git commit -m 'Your message here'
-> Save your staged changes permanently
git push origin main
-> Upload your commits to GitHub
git pull origin main
-> Download latest changes from GitHub
====================================
BRANCHING - Important for Team Work!
git branch
-> List all branches in your repo
git branch feature-login
-> Create a new branch called feature-login
git checkout feature-login
-> Switch to that branch
git checkout -b feature-login
-> Create AND switch in ONE command!
git merge feature-login
-> Merge branch into your current branch
git branch -d feature-login
-> Delete branch after merging
====================================
UNDO MISTAKES - Life Savers!
git restore filename.py
-> Undo unsaved changes in a file
git reset HEAD~1
-> Undo last commit but keep the changes
git revert <commit-id>
-> Safely undo a commit already pushed
git stash
-> Temporarily hide your current changes
git stash pop
-> Bring back your stashed changes
====================================
VIEWING HISTORY
git log
-> Full commit history with details
git log --oneline
-> Short commit history (one line each)
git diff
-> See exactly what changed line by line
git blame filename.py
-> See who changed which line and when
====================================
TOP 5 GIT INTERVIEW QUESTIONS:
1. What is the difference between git merge
and git rebase?
2. What is a pull request and how does it work?
3. How do you resolve a merge conflict?
4. What is git stash and when do you use it?
5. Difference between git reset and git revert?
====================================
Save this post - revise before every interview!
Get FREE projects with Git setup included:
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#GitCheatSheet #Git #GitHub #VersionControl
#GitCommands #DevTools #GitBranching
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#CodingInterview #TechInterview #OpenSource
#ProjectWithSourceCodes #StudentsOfIndia
Commands Every Developer Must Know!
====================================
Git is asked in EVERY tech interview!
TCS, Wipro, Infosys, startups, product cos
ALL expect you to know Git. Master these!
====================================
FIRST TIME SETUP
git config --global user.name 'Your Name'
git config --global user.email 'you@email.com'
-> Run once after installing Git
====================================
STARTING A PROJECT
git init
-> Start tracking a new project folder
git clone <url>
-> Download a repo from GitHub to your PC
====================================
DAILY COMMANDS (Use Every Day!)
git status
-> See which files changed or are new
git add .
-> Stage ALL changed files for commit
git add filename.py
-> Stage one specific file only
git commit -m 'Your message here'
-> Save your staged changes permanently
git push origin main
-> Upload your commits to GitHub
git pull origin main
-> Download latest changes from GitHub
====================================
BRANCHING - Important for Team Work!
git branch
-> List all branches in your repo
git branch feature-login
-> Create a new branch called feature-login
git checkout feature-login
-> Switch to that branch
git checkout -b feature-login
-> Create AND switch in ONE command!
git merge feature-login
-> Merge branch into your current branch
git branch -d feature-login
-> Delete branch after merging
====================================
UNDO MISTAKES - Life Savers!
git restore filename.py
-> Undo unsaved changes in a file
git reset HEAD~1
-> Undo last commit but keep the changes
git revert <commit-id>
-> Safely undo a commit already pushed
git stash
-> Temporarily hide your current changes
git stash pop
-> Bring back your stashed changes
====================================
VIEWING HISTORY
git log
-> Full commit history with details
git log --oneline
-> Short commit history (one line each)
git diff
-> See exactly what changed line by line
git blame filename.py
-> See who changed which line and when
====================================
TOP 5 GIT INTERVIEW QUESTIONS:
1. What is the difference between git merge
and git rebase?
2. What is a pull request and how does it work?
3. How do you resolve a merge conflict?
4. What is git stash and when do you use it?
5. Difference between git reset and git revert?
====================================
Save this post - revise before every interview!
Get FREE projects with Git setup included:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#GitCheatSheet #Git #GitHub #VersionControl
#GitCommands #DevTools #GitBranching
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#CodingInterview #TechInterview #OpenSource
#ProjectWithSourceCodes #StudentsOfIndia
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
SQL CHEAT SHEET - Save This!
Most Asked SQL in Tech Interviews!
====================================
SQL is tested in 90% of tech interviews!
TCS, Infosys, Amazon, Flipkart, Data Analyst
roles ALL require strong SQL. Master this!
====================================
BASIC QUERIES
SELECT * FROM employees;
-> Get all rows from table
SELECT name, salary FROM employees
WHERE salary > 50000;
-> Filter rows with condition
SELECT * FROM employees
ORDER BY salary DESC LIMIT 5;
-> Top 5 highest paid employees
SELECT DISTINCT department FROM employees;
-> Get unique departments only
====================================
AGGREGATE FUNCTIONS
SELECT COUNT(*) FROM employees;
-> Total number of rows
SELECT AVG(salary) FROM employees;
-> Average salary
SELECT MAX(salary), MIN(salary) FROM employees;
-> Highest and lowest salary
SELECT department, COUNT(*) as emp_count
FROM employees
GROUP BY department
HAVING COUNT(*) > 5;
-> Departments with more than 5 employees
====================================
JOINS - Most Asked in Interviews!
INNER JOIN - Only matching rows in both tables:
SELECT e.name, d.dept_name
FROM employees e
INNER JOIN departments d ON e.dept_id = d.id;
LEFT JOIN - All from left + matching right:
SELECT e.name, d.dept_name
FROM employees e
LEFT JOIN departments d ON e.dept_id = d.id;
SELF JOIN - Table joined with itself:
SELECT e1.name, e2.name AS manager
FROM employees e1
JOIN employees e2 ON e1.manager_id = e2.id;
====================================
SUBQUERIES - Asked in Advanced Rounds!
Employees earning more than average:
SELECT name FROM employees
WHERE salary > (SELECT AVG(salary) FROM employees);
2nd highest salary (Classic Question!):
SELECT MAX(salary) FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);
Nth highest salary using LIMIT:
SELECT salary FROM employees
ORDER BY salary DESC LIMIT 1 OFFSET N-1;
====================================
WINDOW FUNCTIONS - Modern SQL!
Rank employees by salary:
SELECT name, salary,
RANK() OVER (ORDER BY salary DESC) as rnk
FROM employees;
Row number within each department:
SELECT name, department,
ROW_NUMBER() OVER
(PARTITION BY department ORDER BY salary DESC)
FROM employees;
====================================
TOP 5 SQL INTERVIEW QUESTIONS:
1. Find duplicate records in a table
2. Find employees with no manager (NULL)
3. Find departments with zero employees
4. Find Nth highest salary
5. Difference between WHERE and HAVING?
====================================
PRACTICE FREE ON:
SQLZoo -> sqlzoo.net
HackerRank -> hackerrank.com/domains/sql
LeetCode -> leetcode.com/problemset/database
====================================
Save this before your next interview!
Get FREE projects with database code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SQLCheatSheet #SQL #MySQL #PostgreSQL
#DatabaseInterview #Joins #Subqueries #WindowFunctions
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#DataAnalyst #BackendDeveloper #TechInterview
#ProjectWithSourceCodes #StudentsOfIndia
Most Asked SQL in Tech Interviews!
====================================
SQL is tested in 90% of tech interviews!
TCS, Infosys, Amazon, Flipkart, Data Analyst
roles ALL require strong SQL. Master this!
====================================
BASIC QUERIES
SELECT * FROM employees;
-> Get all rows from table
SELECT name, salary FROM employees
WHERE salary > 50000;
-> Filter rows with condition
SELECT * FROM employees
ORDER BY salary DESC LIMIT 5;
-> Top 5 highest paid employees
SELECT DISTINCT department FROM employees;
-> Get unique departments only
====================================
AGGREGATE FUNCTIONS
SELECT COUNT(*) FROM employees;
-> Total number of rows
SELECT AVG(salary) FROM employees;
-> Average salary
SELECT MAX(salary), MIN(salary) FROM employees;
-> Highest and lowest salary
SELECT department, COUNT(*) as emp_count
FROM employees
GROUP BY department
HAVING COUNT(*) > 5;
-> Departments with more than 5 employees
====================================
JOINS - Most Asked in Interviews!
INNER JOIN - Only matching rows in both tables:
SELECT e.name, d.dept_name
FROM employees e
INNER JOIN departments d ON e.dept_id = d.id;
LEFT JOIN - All from left + matching right:
SELECT e.name, d.dept_name
FROM employees e
LEFT JOIN departments d ON e.dept_id = d.id;
SELF JOIN - Table joined with itself:
SELECT e1.name, e2.name AS manager
FROM employees e1
JOIN employees e2 ON e1.manager_id = e2.id;
====================================
SUBQUERIES - Asked in Advanced Rounds!
Employees earning more than average:
SELECT name FROM employees
WHERE salary > (SELECT AVG(salary) FROM employees);
2nd highest salary (Classic Question!):
SELECT MAX(salary) FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);
Nth highest salary using LIMIT:
SELECT salary FROM employees
ORDER BY salary DESC LIMIT 1 OFFSET N-1;
====================================
WINDOW FUNCTIONS - Modern SQL!
Rank employees by salary:
SELECT name, salary,
RANK() OVER (ORDER BY salary DESC) as rnk
FROM employees;
Row number within each department:
SELECT name, department,
ROW_NUMBER() OVER
(PARTITION BY department ORDER BY salary DESC)
FROM employees;
====================================
TOP 5 SQL INTERVIEW QUESTIONS:
1. Find duplicate records in a table
2. Find employees with no manager (NULL)
3. Find departments with zero employees
4. Find Nth highest salary
5. Difference between WHERE and HAVING?
====================================
PRACTICE FREE ON:
SQLZoo -> sqlzoo.net
HackerRank -> hackerrank.com/domains/sql
LeetCode -> leetcode.com/problemset/database
====================================
Save this before your next interview!
Get FREE projects with database code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SQLCheatSheet #SQL #MySQL #PostgreSQL
#DatabaseInterview #Joins #Subqueries #WindowFunctions
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#DataAnalyst #BackendDeveloper #TechInterview
#ProjectWithSourceCodes #StudentsOfIndia
HackerRank
Solve Programming Questions | HackerRank
A special-purpose language designed for managing data held in a relational database.
SYSTEM DESIGN BASICS - Save This!
Asked in Every Senior + Product Company Round!
====================================
System Design is asked at Adobe, Microsoft,
Flipkart, Razorpay, Swiggy, Uber and ALL
product companies. Learn the basics NOW!
====================================
1. SCALABILITY
Making your app handle more users over time
Vertical Scaling: Add more RAM/CPU to one server
-> Simple but has physical limits
Horizontal Scaling: Add more servers
-> Used by Google, Amazon, Netflix
-> Needs load balancer to distribute traffic
====================================
2. LOAD BALANCER
Distributes incoming requests across servers
so no single server gets overloaded.
Algorithms:
Round Robin -> requests go in rotation
Least Connections -> send to least busy server
IP Hash -> same user always hits same server
Real examples: AWS ALB, Nginx, HAProxy
====================================
3. CACHING
Store frequently accessed data in fast memory
to avoid hitting the database every time.
Redis -> most popular cache tool
CDN -> cache static files (images, CSS, JS)
near users geographically
Cache strategies:
Cache Aside -> app checks cache, then DB
Write Through -> write to cache + DB together
TTL (Time To Live) -> auto-expire cached data
====================================
4. DATABASE DESIGN
SQL (MySQL, PostgreSQL):
-> Structured data, ACID transactions
-> Use for: banking, orders, user accounts
NoSQL (MongoDB, DynamoDB):
-> Flexible schema, high write speed
-> Use for: chat messages, logs, catalogs
Database Sharding:
-> Split data across multiple DB servers
-> Used when one DB cannot handle load
Replication:
-> Master writes, Slaves read
-> Improves read performance + availability
====================================
5. MICROSERVICES vs MONOLITH
Monolith -> one big codebase, simple to start
Microservices -> split into small independent
services (User, Order, Payment, Notification)
When to use Microservices:
Large teams (each team owns one service)
Different scaling needs per service
Example: Netflix, Uber, Amazon all use it
====================================
6. MESSAGE QUEUES
Async communication between services
so they don't have to wait for each other.
Tools: Apache Kafka, RabbitMQ, AWS SQS
Example: Order placed -> Queue -> Notification
service sends email without slowing checkout!
====================================
7. CAP THEOREM
A distributed system can only guarantee 2 of 3:
C - Consistency (all nodes have same data)
A - Availability (always responds)
P - Partition Tolerance (survives network split)
Real systems choose CP or AP based on use case.
====================================
TOP 5 SYSTEM DESIGN INTERVIEW QUESTIONS:
1. Design URL Shortener (like bit.ly)
2. Design Instagram (image storage + feed)
3. Design WhatsApp (real-time messaging)
4. Design Uber (ride matching + maps)
5. Design Netflix (video streaming + CDN)
====================================
Save this - revise before product company rounds!
Get FREE system design projects:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SystemDesign #SystemDesignInterview #LLD #HLD
#Microservices #Kafka #Redis #LoadBalancer
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#ProductCompany #SDE2 #TechInterview #Scalability
#ProjectWithSourceCodes #StudentsOfIndia
Asked in Every Senior + Product Company Round!
====================================
System Design is asked at Adobe, Microsoft,
Flipkart, Razorpay, Swiggy, Uber and ALL
product companies. Learn the basics NOW!
====================================
1. SCALABILITY
Making your app handle more users over time
Vertical Scaling: Add more RAM/CPU to one server
-> Simple but has physical limits
Horizontal Scaling: Add more servers
-> Used by Google, Amazon, Netflix
-> Needs load balancer to distribute traffic
====================================
2. LOAD BALANCER
Distributes incoming requests across servers
so no single server gets overloaded.
Algorithms:
Round Robin -> requests go in rotation
Least Connections -> send to least busy server
IP Hash -> same user always hits same server
Real examples: AWS ALB, Nginx, HAProxy
====================================
3. CACHING
Store frequently accessed data in fast memory
to avoid hitting the database every time.
Redis -> most popular cache tool
CDN -> cache static files (images, CSS, JS)
near users geographically
Cache strategies:
Cache Aside -> app checks cache, then DB
Write Through -> write to cache + DB together
TTL (Time To Live) -> auto-expire cached data
====================================
4. DATABASE DESIGN
SQL (MySQL, PostgreSQL):
-> Structured data, ACID transactions
-> Use for: banking, orders, user accounts
NoSQL (MongoDB, DynamoDB):
-> Flexible schema, high write speed
-> Use for: chat messages, logs, catalogs
Database Sharding:
-> Split data across multiple DB servers
-> Used when one DB cannot handle load
Replication:
-> Master writes, Slaves read
-> Improves read performance + availability
====================================
5. MICROSERVICES vs MONOLITH
Monolith -> one big codebase, simple to start
Microservices -> split into small independent
services (User, Order, Payment, Notification)
When to use Microservices:
Large teams (each team owns one service)
Different scaling needs per service
Example: Netflix, Uber, Amazon all use it
====================================
6. MESSAGE QUEUES
Async communication between services
so they don't have to wait for each other.
Tools: Apache Kafka, RabbitMQ, AWS SQS
Example: Order placed -> Queue -> Notification
service sends email without slowing checkout!
====================================
7. CAP THEOREM
A distributed system can only guarantee 2 of 3:
C - Consistency (all nodes have same data)
A - Availability (always responds)
P - Partition Tolerance (survives network split)
Real systems choose CP or AP based on use case.
====================================
TOP 5 SYSTEM DESIGN INTERVIEW QUESTIONS:
1. Design URL Shortener (like bit.ly)
2. Design Instagram (image storage + feed)
3. Design WhatsApp (real-time messaging)
4. Design Uber (ride matching + maps)
5. Design Netflix (video streaming + CDN)
====================================
Save this - revise before product company rounds!
Get FREE system design projects:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#SystemDesign #SystemDesignInterview #LLD #HLD
#Microservices #Kafka #Redis #LoadBalancer
#BTech2026 #MCA2026 #BCA2026 #PlacementPrep
#ProductCompany #SDE2 #TechInterview #Scalability
#ProjectWithSourceCodes #StudentsOfIndia
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com
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REACT + JS CHEAT SHEET - Save This!
Most Asked in Tech Interviews!
====================================
JS ESSENTIALS:
map / filter / reduce | spread [...arr]
destructuring const {a, b} = obj
async/await + fetch | ES6 arrow functions
REACT HOOKS:
useState -> local state
useEffect -> side effects (API calls, subscriptions)
useContext -> global data without prop drilling
useRef -> DOM access, persist values
useMemo / useCallback -> performance optimization
KEY CONCEPTS: Virtual DOM, props vs state,
controlled components, lifting state up,
keys in lists, conditional rendering
====================================
TOP 5 INTERVIEW QUESTIONS:
1. What is Virtual DOM?
2. props vs state?
3. useEffect dependency array?
4. What is prop drilling?
5. Controlled vs uncontrolled components?
====================================
Save this before your next interview!
Get FREE projects with source code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#ReactJS #JavaScript #Frontend
#PlacementPrep #TechInterview
#BTech2026 #MCA2026 #BCA2026
#ProjectWithSourceCodes #StudentsOfIndia
Most Asked in Tech Interviews!
====================================
JS ESSENTIALS:
map / filter / reduce | spread [...arr]
destructuring const {a, b} = obj
async/await + fetch | ES6 arrow functions
REACT HOOKS:
useState -> local state
useEffect -> side effects (API calls, subscriptions)
useContext -> global data without prop drilling
useRef -> DOM access, persist values
useMemo / useCallback -> performance optimization
KEY CONCEPTS: Virtual DOM, props vs state,
controlled components, lifting state up,
keys in lists, conditional rendering
====================================
TOP 5 INTERVIEW QUESTIONS:
1. What is Virtual DOM?
2. props vs state?
3. useEffect dependency array?
4. What is prop drilling?
5. Controlled vs uncontrolled components?
====================================
Save this before your next interview!
Get FREE projects with source code:
https://t.me/Projectwithsourcecodes
Share with your placement batch!
#ReactJS #JavaScript #Frontend
#PlacementPrep #TechInterview
#BTech2026 #MCA2026 #BCA2026
#ProjectWithSourceCodes #StudentsOfIndia
Telegram
ProjectWithSourceCodes
Free Source Code Projects for Students š | Python | Java | Android | Web Dev | AI/ML | Final Year Projects | BCA ⢠BTech ⢠MCA | Interview Prep | Job Alerts
Website: https://updategadh.com
Website: https://updategadh.com