Manacher

Manacher——最长回文字串

 

//#include<Windows.h>
#include<iostream>
#include<cstring>
using namespace std;
const int maxn = 100010;

char Ma[maxn<< 1];
int Mp[maxn<< 1];
void Manacher(char s[], int len)
{
    int l = 0;
    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;
        }
    }
}
char ss[maxn];
int main()
{
    cin >> ss;
    int len = strlen(ss);
    Manacher(ss, len);
    int ans = 0;
    for (int i = 0; i < 2* len+ 2; i++)
    {
        ans = max(ans, Mp[i] - 1);
        /*cout << Ma[i] << ": " << Mp[i] << endl;*/
    }
    printf("%d\n", ans);
//      system("pause");
    return 0;
}

代码意图很明显了，注释什么的就不需要了。