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Solve LeetCode 3 Longest Substring Without Repeating Characters in C++ using the sliding window

Longest Substring Without Repeating Characters in C++ LeetCode 3 · sliding window · last index array Table of Contents Problem Statement Approach Algorithm C++ Program Input Sample Output Output Explanation Dry Run Flow of Execution Time Complexity Space Complexity Applications Key Points Interview Questions Frequently Asked Questions Conclusion Problem Statement 3. Longest Substring Without Repeating Characters Given a string s , find the length of the longest substring that contains no repeating characters. A substring is a continuous part of the string, so "pwke" is a subsequence of "pwwkew" but not a substring. Approach We use a sliding window . The window is the part of the string between start and end , and we always keep it free of repeated characters. An array lastIndex of size 128 remembers the most recent position of every ASCII ...
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Count Set Bits in an Integer (C Program)

Count Set Bits in C

🔢 Count Set Bits in an Integer (C Program)

#include<stdio.h>
int count_set_bits(int num)
{
    unsigned int mask = (unsigned int)num;
    int count = 0;
    while(mask)
    {
        count += mask & 1;
        mask >>= 1;
    }
    return count; 
}
int main( )
{
    int number;
  //  printf("Enter the number: ");
    scanf("%d", &number);
    int result = count_set_bits(number);
    printf("The count of set bits is %d\\n", result);
}

📘 Explanation:

This program counts the number of set bits (1s) in the binary representation of an integer using bitwise operations.

🔹 `mask & 1` checks the least significant bit (LSB) of the number.
🔹 If it's 1, `count` is incremented.
🔹 The mask is then right-shifted using `mask >>= 1` to check the next bit.
🔹 The loop continues until the entire binary number is processed.

🔸 Note: Casting `num` to `unsigned int` ensures correct behavior for negative numbers (avoiding sign extension).

🔍 Sample Output:

Input:
13

Output:
The count of set bits is 3

🏷️ Keywords:

count set bits C, number of 1s in binary, bitwise AND, C bit manipulation, right shift, count bits using loop

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