hdu1711 Number Sequence kmp模板

#include<bits/stdc++.h>
#define clr(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef long long ll;
const int maxn=1000100;
int a[maxn],b[maxn],f[maxn];
int n,m;
void fail(){
    f[0]=-1;
    for(int j=1;j<m;j++)
    {
        for(int i=f[j-1];;i=f[i]){
            if(b[j]==b[i+1]){
                f[j]=i+1;
                break;
            }else if(i==-1){
                f[j]=-1;
                break;
            }
        }
    } 
}
int kmp(){
    fail();
    int i=0,j=0;
    while(i<n&&j<m){
        if(a[i]==b[j]){
            i++,j++;
        }else if(j==0){
            i++;
        }else{
            j=f[j-1]+1;
        }
    }
//    printf("i:%d  j:%d\n",i,j);
    return j==m?i-m+1:-1;
}
int main(){
    int T;
    cin>>T;
    while(T--)
    {
        cin>>n>>m;
        for(int i=0;i<n;i++)scanf("%d",&a[i]);
        for(int j=0;j<m;j++)scanf("%d",&b[j]);
        printf("%d\n",kmp());
    }
}