最长回文 HDU 3068 （裸的Manacher）

直接看代码：

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#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

const int MAXN = 1e6+7;
const int oo = 1e9+37;

char s[MAXN];
int  p[MAXN];

int Manacher(int N)
{
    int id=0, Max=0;

    for(int i=2; i<N; i++)
    {
        p[i] = 1;

        if(p[id]+id > i)
            p[i] = min(p[id*2-i], p[id]+id-i);

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

        if(p[id]+id < p[i]+i)
            id = i;

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

    return Max;
}

int main()
{
    while(scanf("%s", s) != EOF)
    {
        int N = strlen(s);

        for(int i=N; i>=0; i--)
        {
            s[i+i+2] = s[i];
            s[i+i+1] = '#';
        }
        s[0] = '$';

        printf("%d\n", Manacher(N+N+1));
    }

    return 0;
}