题解 | #密码截取#

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

bool isSymmetry(string s) {
    auto len = s.length();
    for (int i = 0; i < len / 2; i++) {
        if (s[i] != s[len - i - 1]) {
            return false;
        }
    }

    return true;
}

void Decode(string s) {
    auto len = s.length();
    int maxlen = 0;

    if (len == 1) {
        cout << 1;
        return;
    }

    for (int i = 0; i < len; i++) {
        for (int j = i + 1; j < len; j++) {
            if (s[i] == s[j]) {
                string substr = s.substr(i, j - i + 1);
                bool ret = isSymmetry(substr);
                if (ret) {
                    //cout << substr << endl;
                    if (substr.length() > maxlen) {
                        maxlen = substr.length();
                    }
                }
            }
        }

    }

    cout << maxlen << endl;
}

int main() {
    string s;

    while (cin >> s)
    {
        Decode(s);
    }
}
// 64 位输出请用 printf("%lld")