题解 | 密码截取

#include <iostream>
#include <string>

using namespace std;

// 检查字符串是否是回文
bool isPalindrome(const string &s) {
    int start = 0;
    int end = s.size() - 1;
    while (start < end) {
        if (s[start] != s[end]) {
            return false;
        }
        start++;
        end--;
    }
    return true;
}

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

    int n = s.length();
    int maxLength = 0;

    // 检查每个可能的子串
    for (int i = 0; i < n; ++i) {
        for (int j = i; j < n; ++j) {
            string substring = s.substr(i, j - i + 1);
            if (isPalindrome(substring)) {
                maxLength = max(maxLength, j - i + 1);
            }
        }
    }

    cout << maxLength << endl;
    return 0;
}