题解 | #密码截取#

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

int main() {
    string str;
    cin >> str;
    string str_reverse(str);
    reverse(str_reverse.begin(), str_reverse.end());
    for (int i = str.length(); i >= 0; i--) {//字符串从长到短遍历 所以最先满足的一定是满足题目要求的
        for (int j = 0; j <= str.length() - i; j++) {
            string sub = str.substr(j, i);
            string sub_reverse= sub;
            reverse(sub_reverse.begin(), sub_reverse.end());
            if (sub== sub_reverse&&str_reverse.find(sub) != string::npos) {
                cout << sub.length();
                return 0;
            }
        }
    }
    return 0;
}