POJ 2752 Seek the Name, Seek the Fame（KMP）

题目链接：http://poj.org/problem?id=2752

解题思路：

求所有的相同前后缀长度

求出失配数组，沿着失配数组回退直到等于0，最后答案倒序输出一下。

#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

const int N = 4e5 + 5;

char s[N];
int fail[N];
int ans[N];

void kmp(char *s)
{
    int tot = 0;
    int len = strlen(s);
    ans[tot++] = len;
    fail[0] = -1;
    for (int i=0,j=-1;i<len;){
        if (j==-1||s[i]==s[j]){
            i++;j++;
            fail[i] = j;
        }
        else j = fail[j];
    }

    int now = len;
    //printf("now=%d,fail[now]=%d\n",now,fail[now]);
    while (fail[now]){
        //printf("now=%d,fail[now]=%d\n",now,fail[now]);
        ans[tot++] = fail[now];
        now = fail[now];
    }

    for (int i=tot-1;i>=0;i--)
        if (i!=0) printf("%d ",ans[i]);
        else printf("%d",ans[i]);
    printf("\n");
}

int main()
{
    while (~scanf("%s",s)){
        kmp(s);
    }
    return 0;
}