hdu1711KMP

http://acm.hdu.edu.cn/showproblem.php?pid=1711

还是套模板，但要注意在函数kmp中while(i<len1&&j<len2)因为这个错了好多次。。。。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define maxn 1000000+5
int s1[maxn],s2[maxn];
int next[maxn];
int len1,len2;
void getnext()
{
    int i=0,j=-1;
    next[0]=-1;
    while(i<len2)
    {
        if(j==-1||s2[i]==s2[j])
        {
            i++,j++;
            next[i]=j;
        }
        else j=next[j];
    }
}
int kmp()
{
    int i=0,j=0;
    while(i<len1&&j<len2)
    {
        if(j==-1||s1[i]==s2[j])
            i++,j++;
        else j=next[j];
    }
    if(j>=len2)return i-len2+1;
    return 0;
}
int main()
{
//    #ifndef ONLINE_JUDGE
//        freopen("in.txt","r",stdin);
//    #endif // ONLINE_JUDGE
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&len1,&len2);
        for(int i=0;i<len1;i++)
            scanf("%d",&s1[i]);
        for(int j=0;j<len2;j++)
            scanf("%d",&s2[j]);
        memset(next,0,sizeof(next));
        getnext();
        int flag=kmp();
        if(flag!=0)printf("%d\n",kmp());
        else printf("-1\n");
    }
    return 0;
}