Longest palindrome

#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>
 
using namespace std;
 
string longestPalindrome(string s) {
    int n = s.size();
    int start = 0, maxLen = 1;
 
    vector<vector<int>> dp(n, vector<int>(n, 0));
 
    for (int i = 0; i < n; i++) {
        dp[i][i] = 1;
    }
 
    for (int i = 0; i < n - 1; i++) {
        if (s[i] == s[i + 1]) {
            dp[i][i + 1] = 1;
            start = i;
            maxLen = 2;
        }
    }
 
    for (int len = 3; len <= n; len++) {
        for (int i = 0; i < n - len + 1; i++) {
            int j = i + len - 1;
            if (s[i] == s[j] && dp[i + 1][j - 1]) {
                dp[i][j] = 1;
                start = i;
                maxLen = len;
            }
        }
    }
 
    return s.substr(start, maxLen);
}
 
int main() {
    string s;
    cin >> s;
    cout << longestPalindrome(s) << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: RUNTIME ERROR

Test 4

Verdict: RUNTIME ERROR

Test 5

Verdict: RUNTIME ERROR

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: RUNTIME ERROR

Test 8

Verdict: RUNTIME ERROR

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: RUNTIME ERROR

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: RUNTIME ERROR