poj2752

http://poj.org/problem?id=2752

//寻找前子串与后子串相等的子串
#include<iostream>
using namespace std;
char ch[400001];
int next[400001];
int ans[400001];

void solve (char *s, int ls)
{
    int i=0,j=-1;
    next[0] = -1;
    while(i<ls)
    {
        if(j==-1 || s[i]==s[j])
        {
            i++;
            j++;
            next[i] = j;
        }
        else
        {
            j = next[j];
        }
    }
}
int main()
{
    while(cin>>ch)
    {
        memset(ans , 0 ,sizeof(ans));
        int i,j;
        ans[0]=strlen(ch);
        i=0;j=1;
        solve(ch, ans[0]);
        
        while(ans[i++])
        {
            ans[i] = next[ans[i-1]];//从长到短，递归查找前子串和后子串相等的子串
        }
          for(j=i-2;j>=0;j--)
           {
               cout<<ans[j];    
               if(j) cout<<" "; 
          }               
         cout<<endl;
    }    
    return 0;    
}