题解 | #密码截取#

#include <iostream>
using namespace std;

bool is_password(const char* begin, const char* end) {
    while (*begin == *end) {
        ++begin;
        --end;
    }
    return begin >= end;
}

int main() {
    string text;
    while (cin >> text) {
        int max_length = 1;
        for (size_t i = 0; i < text.size(); ++i) {
            const char c = text[i];
            string::size_type pos = text.size();
            do {
                pos = text.find_last_of(c, pos - 1);
                if (is_password(&text[i], &text[pos])) {
                    int length = pos - i + 1;
                    if (length > max_length) {
                        max_length = length;
                    }
                }
            } while (pos > i);

        }
        cout << max_length << endl;
    };
}
// 64 位输出请用 printf("%lld")