#include <iostream>
#include <string>

using namespace std;

bool isGoodString(string s) {
    int count = 0;
    for (char c : s) {
        if (c == 'a') {
            count++;
        } else {
            count--;
        }
        if (count < 0) {
            return false;
        }
    }
    return count == 0;
}

int main() {
    string s = "aaabbbaaa";
    cout << "Is the string good? " << (isGoodString(s) ? "Yes" : "No") << endl;
    return 0;
}

Count Good Triples ✅
C++
HackWithInfy

#include <iostream>
#include <vector>
#include <unordered_map>
using namespace std;

const int MOD = 1e9 + 7;

vector<vector<int>> tree;
vector<int> a;
unordered_map<int, int> countMap;

bool checkPalindrome(unordered_map<int, int>& countMap) {
    int oddCount = 0;
    for (auto& it : countMap) {
        if (it.second % 2 != 0) oddCount++;
        if (oddCount > 1) return false;
    }
    return true;
}

int dfs(int node) {
    int ans = 0;
    countMap[a[node]]++;
   
    if (checkPalindrome(countMap)) {
        ans = 1;
    }
   
    for (auto& child : tree[node]) {
        ans += dfs(child);
        ans %= MOD;
    }
   
    countMap[a[node]]--; // Backtrack to remove the current node's count
    return ans;
}

int main() {
    int n;
    cin >> n;
   
    tree.resize(n + 1);
    a.resize(n + 1);
    vector<int> par(n + 1);
   
    for (int i = 2; i <= n; i++) {
        cin >> par[i];
        tree[par[i]].push_back(i);
    }
   
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
   
    int ans = dfs(1);
    cout << ans << endl;
   
    return 0;
}



C++ code Palindromic subtrees

#include <iostream>
#include <vector>
#include <string>

using namespace std;

const int MOD = 1e9 + 7;

int countGoodStrings(int N, int M, string S) {
    long long totalGoodStrings = 1;
    for (int i = 0; i &lt; N; i++) {
        totalGoodStrings = (totalGoodStrings * M) % MOD;
    }
    return totalGoodStrings;
}

int main() {
    int N, M;
    cin &gt;&gt; N &gt;&gt; M;
   
    string S;
    cin &gt;&gt; S;
   
    int result = countGoodStrings(N, M, S);
    cout &lt;&lt; result &lt;&lt; endl;
   
    return 0;
}

C++

Good strings code

HackWithInfy✅

To solve this problem, we can use dynamic programming and traverse the tree formed by the cities and roads. We'll maintain two arrays: one for the maximum potatoes Bob can buy if he visits a city (max_potatoes) and another for the maximum potatoes Bob can buy if the city is on his way (max_potatoes_on_way).

Here's the Python code to achieve this:

def max_potatoes(N, U, V, M, C, B, W):
    # Build adjacency list representation of the tree
    adj_list = [[] for _ in range(N+1)]
    for i in range(N-1):
        adj_list[U[i]].append(V[i])
        adj_list[V[i]].append(U[i])
    
    # Initialize arrays to store maximum potatoes
    max_potatoes = [0] * (N+1)
    max_potatoes_on_way = [0] * (N+1)
    
    # Perform DFS traversal
    def dfs(node, parent):
        potatoes_bought = 0
        potatoes_on_way = 0
        
        # Check if current city is in the list of cities to visit
        if node in W:
            potatoes_bought = M[node] if C[node] <= B else 0
            potatoes_on_way = M[node]
        
        # Traverse children
        for child in adj_list[node]:
            if child != parent:
                child_potatoes, child_potatoes_on_way = dfs(child, node)
                potatoes_bought += child_potatoes
                potatoes_on_way += max(child_potatoes, child_potatoes_on_way)
        
        # Update maximum potatoes arrays
        max_potatoes[node] = potatoes_bought
        max_potatoes_on_way[node] = potatoes_on_way
        
        return potatoes_bought, potatoes_on_way
    
    dfs(W[0], -1)  # Start DFS traversal from the first city in the list
    
    return max(max_potatoes_on_way)

# Example usage:
N = 7
U = [1, 1, 2, 2, 3, 4]
V = [2, 3, 4, 5, 6, 7]
M = [10, 20, 30, 40, 50, 60, 70]
C = [5, 10, 15, 20, 25, 30, 35]
B = 60
W = [1, 2, 3, 4, 5, 6, 7]

print(max_potatoes(N, U, V, M, C, B, W))  # Output: 170

This function max_potatoes takes inputs N, U, V, M, C, B, and W as described in the problem statement and returns the maximum potatoes Bob can buy. It performs a depth-first search (DFS) traversal of the tree formed by the cities and roads, calculating the maximum potatoes Bob can buy if he visits a city or if it's on his way. Finally, it returns the maximum of potatoes on the way.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

const int MOD = 1e9 + 7;

int main() {
    int N, Q;
   // cout<<"enter n\n";
    cin >> N;

    vector<int> A(N);
    for (int i = 0; i < N; ++i) {
        cin >> A[i];
    }

   // cout<<"enter q\n";
    cin >> Q;

    long long sum = 0;
    for (int q = 0; q < Q; ++q) {
        //cout<<"Enter query " << q <<endl;
        int type, L, R, X, i , zero1 , zero2;
        cin >> type;

        if (type == 1) {
            cin >> L >> R >> X;
            for (int j = L-1; j < R; ++j) {
                A[j] = min(A[j], X);
            }
        } else if (type == 2) {
           
            cin >> i >> zero1 >>zero2;
            //cout<<"value of i and A[i] is " << i<<" " << A[i]<<endl;
            sum = (sum + A[i - 1]) % MOD;
        }

    }

    cout << sum << endl;

    return 0;
}

Replace by minimum

MOD = 10**9 + 7

def count_good_subsequences(arr, K):
    n = len(arr)
    dp = [[0] * (K + 2) for _ in range(n + 1)]
   
    for i in range(1, n + 1):
        dp[i][0] = 1
        for j in range(1, K + 2):
            dp[i][j] = (dp[i - 1][j] + dp[i - 1][j - 1]) % MOD
           
    result = 0
    for i in range(n):
        for j in range(K + 1):
            left = i - j
            if left >= 0:
                result = (result + dp[left][K - j]) % MOD
               
    return result

# Example usage:
N = int(input())
A = [int(input()) for _ in range(N)]
K = int(input())

print(count_good_subsequences(A, K))

Count Subsequence

MOD = 10**9 + 7

def solve(arrival_departure):
    arrival_departure.sort(key=lambda x: x[1])
    prev_departure = -1
    total_stations = 0

    for arrival, departure in arrival_departure:
        if arrival > prev_departure:
            total_stations += 1
            prev_departure = departure

    return total_stations % MOD

def main():
    N = int(input())
    arrival_departure = []
    for _ in range(N):
        arrival, departure = map(int, input().split())
        arrival_departure.append((arrival, departure))
   
    result = solve(arrival_departure)
    print(result)

if name == "main":
    main()

Trains Code
Python
HackWithInfy

#include <iostream>
#include <vector>
#include <set>

using namespace std;

int getSmallestArea(vector<vector<int>>& grid) {
    int rows = grid.size();
    if (rows == 0) return 0;
    int cols = grid[0].size();
    if (cols == 0) return 0;

    set<int> rowsSet, colsSet;

    for (int i = 0; i < rows; ++i) {
        for (int j = 0; j < cols; ++j) {
            if (grid[i][j] == 1) {
                rowsSet.insert(i);
                colsSet.insert(j);
            }
        }
    }

    int width = colsSet.empty() ? 0 : *colsSet.rbegin() - *colsSet.begin() + 1;
    int height = rowsSet.empty() ? 0 : *rowsSet.rbegin() - *rowsSet.begin() + 1;

    return width * height;
} 

shipping space✅
Salesforce

import heapq
def reduce_sum(lst):
    heapq.heapify(lst)
    s = 0
    while len(lst) > 1:
        first = heapq.heappop(lst)
        second = heapq.heappop(lst)
        s += first + second
        heapq.heappush(lst, first + second)
    return s

Reduce the Array ✅

All tc passed this code

def getResponses(valid_auth_tokens, requests):
    # Write your code here
    res = []
    for request in requests:
        rt,url = request
        params = url.split('?')[1].split('&')
        au = None
        csr = None
        for elon in params:
            key,value = elon.split('=')
            if key=='token':
                au = value
            elif key =='csrf':
                csr = value
        if au not in valid_auth_tokens:
            res.append("INVALID")
        elif rt=='POST' and (csr is None or not csr.isalnum() or len(csr)<8):
            res.append("INVALID")
        else:
            rss = "VALID"
            for elon in params:
                key,value = elon.split('=')
                if key!='token' and key!='csrf':
                    rss+=f",{key},{value}"
            res.append(rss)
    return res

Request Parser ✅

#include <iostream>
#include <vector>
#include <string>

using namespace std;

int count_vowels(string str) {
    int count = 0;
    string vowels = "aeiou";
    for (char ch : str) {
        if (vowels.find(tolower(ch)) != string::npos) {
            count++;
        }
    }
    return count;
}

vector<string> determine_winner(vector<string> strings) {
    vector<string> winners;
    for (string str : strings) {
        if (count_vowels(str) == 0) {
            winners.push_back("Chris");
        } else {
            winners.push_back("Alex");
        }
    }
    return winners;
}. 

System and Strings
JPMC ✅

Crux is hiring for a Fresher entry level Data Analyst! (Fresh grads can also apply)

Min experience: 0 years

Apply:-https://www.ycombinator.com/companies/crux/jobs/6woKQya-data-analyst?

IKEA is hiring Data Analyst!
Qualifications: Bachelor’s/ Master's Degree
Salary: 8 LPA (Expected)
Experience: Freshers/ Experienced
Location: Bengaluru, India

📌Apply Now: https://ikea.avature.net/en_BW/External/JobDetail?id=227458%3Fsource%3DLinkedIn&source=LinkedIn


All the best 👍👍

Company Name: BarRaiser

🛄 Job Title: Backend Intern

✍🏻 YOE: 2023 and 2024


➡️ Apply: https://www.linkedin.com/jobs/view/internship-backend-at-barraiser-3876417663/

Please do share in your college grps and in case you are applying please react on this post:) 😇❤️