牛客题霸--最长回文子串题解

题目链接牛客题霸--最长回文子串题解
来源：牛客网

马拉车算法求最长回文子串

class Palindrome {
public:
int getLongestPalindrome(string A, int n) {
string str = "@#";
int p[100010], id = 0, mx = -1, maxn = -1;
memset(p, 0, sizeof(p));

    for ( int i = 0; i < n; i++ ) {
        str += A[i];
        str += '#';
    }

    for ( int i = 0; i < str.size(); i++ ) {
        if ( i < mx ) p[i] = min(p[ id * 2 - i], mx - i);
        else p[i] = 1;

        while ( str[i-p[i]] == str[i + p[i]]) p[i]++;

        if ( p[i] + i > mx) {
            id = i;
            mx = p[i] + i;
        }

        maxn = max(maxn, p[i]-1);
    }
    return maxn;
}

};