kmp——官渡之战

#include <cstdio>  
#include <iostream>  
#include <cstring>  
using namespace std;  
  
const int N = 1000002;  
int Next[N];  
char S[N], T[N];  
int slen, tlen;//注意每次一定要计算长度  
  
void getNext()  
{  
    int j, k;  
    j = 0; k = -1; Next[0] = -1;  
    while(j < tlen)  
        if(k == -1 || T[j] == T[k])  
            Next[++j] = ++k;  
        else  
            k = Next[k];  
  
} 
int KMP_Index()  
{  
    int i = 0, j = 0;  
    getNext();  
  
    while(i < slen && j < tlen)  
    {  
        if(j == -1 || S[i] == T[j])  
        {  
            i++; j++;  
        }  
        else  
            j = Next[j];  
    }  
    if(j == tlen)  
        return 1;  
    else if(i>=slen)
    {
    	for(i=0;i<slen;i++)
    	{
    		if(S[i]!=T[j])
    		{
    			return -1;
			}
    		j++;
    		if(j>=tlen)
    		return 1;
		}
	}
        return -1;  
}  
int main()  
{  
  
    int TT;  
    int i, cc;  
        while(scanf("%s",S)!=EOF)
		{  
        scanf("%s",T);  
        slen = strlen(S);  
        tlen = strlen(T);
        if(KMP_Index()==1)
		printf("yes\n");
		else
		printf("no\n");
		} 
    return 0;  
}