Longest Palindromic Substring in C++

Welcome to the Longest Palindromic Substring in C++ page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

#include <iostream>
#include <string>
#include <cstring>

#define MAX_LENGTH 1000

int expandAroundCenter(const std::string& s, int left, int right) {
    while (left >= 0 && right < s.length() && s[left] == s[right]) {
        left--;
        right++;
    }
    return right - left - 1;
}

bool longestPalindromicSubstring(const std::string& s, std::string& result) {
    if (s.empty()) {
        result = "";
        return false;
    }

    int start = 0, maxLength = 0;
    int len = s.length();

    for (int i = 0; i < len; i++) {
        int len1 = expandAroundCenter(s, i, i);
        int len2 = expandAroundCenter(s, i, i + 1);
        int len = (len1 > len2) ? len1 : len2;

        if (len > maxLength) {
            start = i - (len - 1) / 2;
            maxLength = len;
        }
    }

    if (maxLength > 1) {
        result = s.substr(start, maxLength);
        return true;
    }

    result = "";
    return false;
}

int main(int argc, char* argv[]) {
    if (argc != 2) {
        std::cout << "Usage: please provide a string that contains at least one palindrome" << std::endl;
        return 1;
    }

    std::string input = argv[1];
    std::string result;

    if (longestPalindromicSubstring(input, result) && !result.empty()) {
        std::cout << result << std::endl;
    } else {
        std::cout << "Usage: please provide a string that contains at least one palindrome" << std::endl;
    }

    return 0;
}

Longest Palindromic Substring in C++ was written by:

• Meet Thakur

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.