字符串哈希

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
typedef unsigned long long ull;
#define int ull
const int N=1e6+10;
const int b=31;
char s1[N],s2[N];
int power[N],H[N];
signed main(){
	power[0]=1;
	for(int i=1;i<N;i++){
		power[i]=power[i-1]*b;
	}
	int t;
	cin>>t;
	while(t--){
		scanf("%s%s",s1+1,s2+1);
		int n=strlen(s1+1),m=strlen(s2+1);
		H[0]=0;
		for(int i=1;i<=m;i++){
			H[i]=(H[i-1]*b+int(s2[i]-'A'+1));
		}
		int s=0;
		for(int i=1;i<=n;i++){
			s=s*b+int(s1[i]-'A'+1);
		}
		int ans=0;
		for(int i=0;i+n<=m;i++){
			if(s==H[i+n]-H[i]*power[n]){
				ans++;
			}
		}
		cout<<ans<<endl;
	}
}