poj 2752(KMP)

poj 2752
1、注意f数组的意思就是前缀和后缀最长公共部分长度，灵话运用解题

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
#define ms(i,j) memset(i, j, sizeof i);

const int MAXN = 400000 + 5;

char s[MAXN];
int f[MAXN], n, ans[MAXN], tot;

void init()
{
    n = strlen(s);
}
void solve()
{
    f[0] = f[1] = 0;
    for (int i=1;i<n;i++)
    {
        int j = f[i];
        while (j && s[i]!=s[j]) j = f[j];
        f[i+1] = (s[i]==s[j]) ? (j+1) : (0);
    }
    int i = n; tot = 0;
    while (i)
    {
        int xh = i - f[i];
        ans[++tot] = i;
        i = f[i];
    }
    bool flag = false;
    for (int i=tot;i>0;i--)
    {
        if (flag) printf(" ");
        printf("%d", ans[i]);
        flag = true;
    }
    printf("\n");
}
int main()
{
    while (scanf("%s", s)==1)
    {
        init();
        solve();
    }
    return 0;
}