POJ3461 字符串双HASH

#include<iostream>
#include<cstdio>
#include<cstring> 
#define ull unsigned long long
using namespace std;
const ull B=1e8+5,C=1e8+7;
const int maxn=100001;    
char a[maxn],b[maxn*100];    
int ans;
int al,bl;
int find(){
    int i;
    al=strlen(a);
    bl=strlen(b);
    if(al>bl)return -1;   
    ull t=1,ah=0,bh=0,ah1=0,bh1=0;
    for(i=0;i<al;i++){
	    t*=B;
	    ah=ah*B+a[i];ah1=ah1*B+a[i];
	    bh=bh*B+b[i];bh1=bh1*B+b[i];
	}
	for(i=0;i+al<=bl;i++){    
        if(ah==bh && ah1==bh1)ans++;    
        if(i+al<bl)bh=bh*B+b[i+al]-b[i]*t;
		if(i+al<bl)bh1=bh1*B+b[i+al]-b[i]*t;    
    }     
    return ans;
}
int main(){
	int i,j,k,m,n;
	int t;
	scanf("%d",&t);
	getchar();
	while(t--){
		ans=0;
	    gets(a);
	    gets(b);
	    cout<<find()<<endl;
	}
	return 0;
}