求字符串中出现过的最长回文子串

const int MAXN = 110010;
//字符串长度<MAXN
char Ma[MAXN * 2];
int Mp[MAXN * 2];
int Manacher(char s[]) {
	int l = 0, len = strlen(s);
	Ma[l++] = '$';
	Ma[l++] = '#';
	for (int i = 0; i<len; i++)  {
		Ma[l++] = s[i];
		Ma[l++] = '#';
	}
	Ma[l] = 0;
	int mx = 0, id = 0;
	for (int i = 0; i<l; i++)  {
		Mp[i] = mx>i ? min(Mp[2 * id - i], mx - i) : 1;
		while (Ma[i + Mp[i]] == Ma[i - Mp[i]])Mp[i]++;
		if (i + Mp[i]>mx)   {
			mx = i + Mp[i];    id = i;
		}
	}
	int ans = 0;
	for (int i = 0; i<2 * len + 2; i++)
		ans = max(ans, Mp[i] - 1);
	return ans;
}

Manacher模版