poj2752 Seek the Name, Seek the Fame

地址：http://poj.org/problem?id=2752

题目：

Seek the Name, Seek the Fame

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 18711		Accepted: 9607

Description

The little cat is so famous, that many couples tramp over hill and dale to Byteland, and asked the little cat to give names to their newly-born babies. They seek the name, and at the same time seek the fame. In order to escape from such boring job, the innovative little cat works out an easy but fantastic algorithm: 

Step1. Connect the father's name and the mother's name, to a new string S. 
Step2. Find a proper prefix-suffix string of S (which is not only the prefix, but also the suffix of S). 

Example: Father='ala', Mother='la', we have S = 'ala'+'la' = 'alala'. Potential prefix-suffix strings of S are {'a', 'ala', 'alala'}. Given the string S, could you help the little cat to write a program to calculate the length of possible prefix-suffix strings of S? (He might thank you by giving your baby a name:) 

Input

The input contains a number of test cases. Each test case occupies a single line that contains the string S described above. 

Restrictions: Only lowercase letters may appear in the input. 1 <= Length of S <= 400000. 

Output

For each test case, output a single line with integer numbers in increasing order, denoting the possible length of the new baby's name.

Sample Input

ababcababababcabab
aaaaa

Sample Output

2 4 9 18
1 2 3 4 5

Source

POJ Monthly--2006.01.22,Zeyuan Zhu

思路：next数组的应用

#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;

#define MP make_pair
#define PB push_back
typedef long long LL;
const double eps=1e-8;
const int K=1e6+7;
const int mod=1e9+7;

int nt[K],ans[K];
char sa[K],sb[K];
void kmp_next(char *T,int *next)
{
    next[0]=0;
    for(int i=1,j=0,len=strlen(T);i<len;i++)
    {
        while(j&&T[i]!=T[j]) j=next[j-1];
        if(T[i]==T[j])  j++;
        next[i]=j;
    }
}
int kmp(char *S,char *T,int *next)
{
    int ans=0;
    int ls=strlen(S),lt=strlen(T);
    kmp_next(T,next);
    for(int i=0,j=0;i<ls;i++)
    {
        while(j&&S[i]!=T[j]) j=next[j-1];
        if(S[i]==T[j])  j++;
        if(j==lt)   ans++;
    }
    return ans;
}
int main(void)
{
    while(1==scanf("%s",sa))
    {
        kmp_next(sa,nt);
        int t=strlen(sa)-1,cnt=1;
        ans[cnt++]=t+1;
        while(nt[t])
        {
            ans[cnt++]=nt[t];
            t=nt[t-1];
        }
        for(int i=cnt-1;i;i--)
            printf("%d ",ans[i]);
        printf("
");
    }
    return 0;
}