2. Control Structures

Control structures help us control the flow of our program, meaning they decide which code runs and when.


1. if, elif, else

Used for decision making.

Syntax:

if condition:
    # code runs if condition is True
elif another_condition:
    # code runs if first is False but this is True
else:
    # runs if all conditions are False

✅ Example:

num = 10
if num > 0:
    print("Positive number")
elif num == 0:
    print("Zero")
else:
    print("Negative number")

2. Loops (for, while)

for loop – repeats code a fixed number of times.

for i in range(1, 6):
    print("Number:", i)

while loop – repeats code while a condition is true.

count = 1
while count <= 5:
    print("Count:", count)
    count += 1

3. break, continue, pass

break → stops the loop completely.

continue → skips the current iteration, goes to next.

pass → does nothing (just a placeholder).


✅ Example:

for i in range(1, 6):
    if i == 3:
        continue   # skips number 3
    if i == 5:
        break      # stops loop at 5
    print(i)

4. Nested loops & conditions

Loop inside another loop.

Condition inside another condition.


✅ Example: Multiplication Table (2 to 3)

for i in range(2, 4):      # outer loop
    for j in range(1, 6):  # inner loop
        print(i, "x", j, "=", i * j)
    print("------")

Practice Problems

1. Print the multiplication table of 5

for i in range(1, 11):
    print("5 x", i, "=", 5 * i)

2. Find the largest of three numbers

a = 10
b = 25
c = 15

if a >= b and a >= c:
    largest = a
elif b >= a and b >= c:
    largest = b
else:
    largest = c

print("The largest number is:", largest)

🎊 Happy New Year 2018 E.C.! 🎊
Wishing you a peaceful, healthy, and successful year ahead. Melkam Addis Amet! 🌸

🐍 Python Data Structures

1️⃣ Strings

A string is text inside quotes:

"Hello".

Useful methods:

upper() → make all letters BIG.

lower() → make all letters small.

split() → cut the string into a list by spaces or a chosen separator.

replace("old","new") 

→ change part of the text.

Slicing → pick part of the string:

text[0:5].

2️⃣ Lists

A list stores many items in order:

fruits = ["apple", "banana", "orange"]

Common methods:

append(x) → add item at the end.

remove(x) → delete by value.

pop(i) → delete by position (default last).

sort() → arrange items in order.


3️⃣ Tuples

A tuple is like a list but cannot change (immutable):

colors = ("red", "green", "blue")

4️⃣ Sets

A set stores unique items (no duplicates):

nums = {1, 2, 3}

Useful operations:

union() → join two sets.

intersection() → common items of two sets.


5️⃣ Dictionaries

A dictionary stores key : value pairs:

student = {"name": "Ali", "age": 20}

Methods:

keys() → all keys.

values() → all values.

items() → key–value pairs.


🏋️ Practice Tasks

1. Word Frequency
Count how many times each word appears:

sentence = "python is easy and python is fun"
words = sentence.split()
count = {}
for w in words:
    count[w] = count.get(w, 0) + 1
print(count)

2. Highest Mark
Store 5 students and marks, then print the top scorer:

students = {
    "Ali": 88,
    "Sara": 95,
    "Musa": 76,
    "Hana": 90,
    "Omar": 82
}
top = max(students, key=students.get)
print("Highest:", top, students[top])

✅ Tip: Remember

Use list when data changes.

Use tuple when data stays fixed.

Use set to keep only unique values.

Use dictionary to link keys and values.

🌟 What is AI (Artificial Intelligence)?

Artificial Intelligence (AI) means making machines or computers think and act like humans.
It allows computers to learn from experience, understand language, recognize images, make decisions, and even solve problems.


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🧠 Main Idea of AI

AI is built to:

Learn from data and experiences (like humans learn from practice).

Reason by making decisions or predictions.

Act by performing tasks intelligently.


Example:
When you ask Google Assistant or ChatGPT a question, it uses AI to understand your words and respond smartly.


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⚙️ Types of AI

1. Narrow AI (Weak AI)

Works for one specific task.

Example: Siri, Google Assistant, or face recognition on your phone.


2. General AI (Strong AI)

Thinks and learns like a human.

It can do any intelligent task.

(This type doesn’t fully exist yet.)


3. Super AI

Smarter than humans in every way.

Only an idea right now, not real yet.



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🧩 Main Branches of AI

Branch Description Example

Machine Learning (ML) Teaches computers to learn from data Netflix recommending movies
Deep Learning Uses artificial neural networks like the human brain Self-driving cars
Natural Language Processing (NLP) Helps computers understand human language ChatGPT, Google Translate
Computer Vision Allows computers to see and understand images/videos Face recognition
Robotics Makes robots that can act like humans Robot assistants
Expert Systems Gives expert-level decisions Medical diagnosis software



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🚀 Uses of AI in Real Life

🤖 Healthcare – diagnosing diseases

🏦 Banking – detecting fraud

🛒 E-commerce – recommending products

🚗 Transportation – self-driving cars

📱 Phones – voice assistants

🏫 Education – smart tutoring systems



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⚖️ Advantages of AI

✅ Works 24/7 without getting tired
✅ Makes fast and accurate decisions
✅ Helps in dangerous jobs
✅ Can analyze large data quickly


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⚠️ Disadvantages of AI

❌ Expensive to develop
❌ Can cause unemployment
❌ May make humans too dependent
❌ Risk of misuse (like fake information or hacking)


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💬 Simple Example

If you tell your phone,

> “Play my favorite song,”



The AI in your phone:

1. Understands your speech (NLP),


2. Searches your song list (Machine Learning),


3. Plays your favorite song (Action).

Python operators