Longest palindrome

#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>
 
using namespace std;
 
string longestPalindrome(string &s) {
    int n = s.size();
    vector<vector<bool>> dp(n, vector<bool>(n, false));
 
    int maxLen = 1;
    for (int i = 0; i < n; ++i)
        dp[i][i] = true;
 
    int start = 0;
    for (int i = 0; i < n - 1; ++i) {
        if (s[i] == s[i + 1]) {
            dp[i][i + 1] = true;
            start = i;
            maxLen = 2;
        }
    }
 
    for (int k = 3; k <= n; ++k) {
        for (int i = 0; i < n - k + 1; ++i) {
            int j = i + k - 1;
 
            if (dp[i + 1][j - 1] && s[i] == s[j]) {
                dp[i][j] = true;
 
                if (k > maxLen) {
                    start = i;
                    maxLen = k;
                }
            }
        }
    }
 
    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