Shortest palindrome

#include <iostream>
#include <string>
#include <climits>
using namespace std;

int shortestPalindrome(const string &s) {
    int n = s.length();
    int min_len = INT_MAX;

    auto expandAroundCenter = [&](int left, int right) {
        while (left >= 0 && right < n && s[left] == s[right]) {
            if (right - left + 1 >= 2) {
                min_len = min(min_len, right - left + 1);
            }
            left--;
            right++;
        }
    };

    for (int i = 0; i < n - 1; i++) {
        expandAroundCenter(i, i);
        expandAroundCenter(i, i + 1);
    }

    if (min_len == INT_MAX) {
        return -1;
    }

    return min_len;
}

int main() {
    string s;
    cin >> s;

    int result = shortestPalindrome(s);
    cout << result << endl;

    return 0;
}

Test 1

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Test 68

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