题解 | #最长回文子串#

#include <iostream>
using namespace std;

int main() {
    string str;
    getline (cin, str);
    int count1 = 0, count2 = 1, maxn = 0, pos = 1;
    for (int i = 0; i < str.length(); i++) {      //abcba型对称回文串的计算
        while (str[i - pos] == str[i + pos]) {
            count2 += 2;
            pos += 1;
            maxn = max(count2, maxn);
            if (str[i - pos] != str[i + pos]) {
                count2 =1;
                pos =1;
                break;
            }
        }
        while (str[i] == str[i + pos]) {      //abba型对称回文串的计算
            count1 += 2;
            pos += 2;
            maxn = max(count1, maxn);
            i -= 1;
            if (str[i] != str[i + pos] || i <0) {
                i += (count1 / 2 + 1);
                count1 = 0;
                pos = 1;
            }
        }
    }
    cout << maxn << endl;
}