POJ 2752 KMP 待AC

求相等前后缀长度

代码：

#include <cstdio>
#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#define sf scanf
#define pf printf
using namespace std;
const int maxn = 400000 + 50;
char str[maxn],fail[maxn];

int getFail(){
    int len = strlen(str);
    fail[0] = fail[1] = 0;
    for(int i = 1;i < len;++i){
        int j = fail[i];
        while(j && str[j] != str[i]) j = fail[j];
        fail[i + 1] = (str[j] == str[i]  ? j + 1 : 0);
    }
    return len;
}

int ans[maxn],cnt;
int main(){
//    freopen("data.txt","r",stdin);
    while(sf("%s",str) != EOF){
        int len = getFail();
        int j = fail[len];
        cnt = 0;
        while(j){
            ans[++cnt] = j; j = fail[j];
        }
        for(int i = cnt;i;--i){
            pf("%d ",ans[i]);
        }pf("%d\n",len);
    }
    return 0;
}