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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 ...

Recursive String Reversal in C

Recursive String Reversal in C

✅ Recursive String Reversal in C

#include <stdio.h>
#include <string.h>

// Recursive function to reverse the string
void reverseString(char str[], int start, int end) {
    if (start >= end)
        return;

    // Swap characters
    char temp = str[start];
    str[start] = str[end];
    str[end] = temp;

    // Recur for next pair
    reverseString(str, start + 1, end - 1);
}

int main() {
    char str[100];
    printf("Enter a string:\n");
    scanf(" %[^\n]", str);  // Read string with spaces

    printf("Original String: %s\n", str);
    
    reverseString(str, 0, strlen(str) - 1);

    printf("Reversed String: %s\n", str);

    return 0;
}
  

๐Ÿ“˜ Explanation:

This program demonstrates how to reverse a string using a recursive approach:

  • It defines a recursive function reverseString() that swaps characters from the beginning and end, moving toward the center.
  • Base case: if start >= end, the function returns.
  • Each recursive call handles the next inner pair of characters.
  • scanf(" %[^\n]", str) reads input including spaces.

๐Ÿงพ Sample Output:

Enter a string:
hello world
Original String: hello world
Reversed String: dlrow olleh
  

๐Ÿ”‘ Keywords:

Recursion in C, reverse string recursively, string functions in C, string reverse logic, string manipulation, reverse using function

๐Ÿ“Œ Hashtags:

#CProgramming #Recursion #StringReversal #BeginnerC #CodeWithC #StringLogic

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