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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 ...

Check Palindrome and Reverse String in C

Check Palindrome and Reverse String in C

✅ Check Palindrome and Reverse a String in C

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

// Function to check if string is palindrome
int pal(char str[]) {
    int left = 0, right = strlen(str) - 1;
    while (left < right) {
        if (str[left] != str[right]) {
            printf("No, Entered string is not a palindrome.\\n");
            return 0;
        }
        left++;
        right--;
    }
    printf("Yes, Entered string is a palindrome.\\n");
    return 1;
}

// Function to reverse the string
void reverse(char str[]) {
    int start = 0, end = strlen(str) - 1;
    while (start < end) {
        char temp = str[start];
        str[start] = str[end];
        str[end] = temp;
        start++;
        end--;
    }
}

int main() {
    char str[100];
    printf("Enter the string:\\n");
    scanf(" %[^\n]", str);

    printf("Before Reversing: %s\\n", str);
    pal(str);              // Check palindrome before reversing
    reverse(str);
    printf("After Reversing: %s\\n", str);

    return 0;
}
  

๐Ÿ“˜ Explanation:

✅ This program reads a string from the user.
✅ It first checks whether the input string is a palindrome by comparing characters from both ends.
✅ If the string is not a palindrome, it notifies the user.
✅ Then it reverses the string using a two-pointer method and prints the reversed result.
✅ It uses strlen, scanf, and character swapping.

๐Ÿงพ Sample Output:

Enter the string:
madam
Before Reversing: madam
Yes, Entered string is a palindrome.
After Reversing: madam
  

๐Ÿ”‘ Keywords:

Palindrome check C, reverse string in C, C string programs, string palindrome logic, two pointer technique, string manipulation

๐Ÿ“Œ Hashtags:

#CProgramming #PalindromeCheck #ReverseString #StringHandling #BeginnersC #InterviewPrep #StringFunctions

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