A – Number Sequence （KMP模板：第一次出现位次）

InputThe first line of input is a number T which indicate the number of cases. Each case contains three lines. The first line is two numbers N and M (1 <= M <= 10000, 1 <= N <= 1000000). The second line contains N integers which indicate a[1], a[2], …… , a[N]. The third line contains M integers which indicate b[1], b[2], …… , b[M]. All integers are in the range of [-1000000, 1000000].
OutputFor each test case, you should output one line which only contain K described above. If no such K exists, output -1 instead.
Sample Input

2
13 5
1 2 1 2 3 1 2 3 1 3 2 1 2
1 2 3 1 3
13 5
1 2 1 2 3 1 2 3 1 3 2 1 2
1 2 3 2 1

Sample Output

6
-1

题意：KMP找第一次出现模式串的位次，也可以用strstr之类的函数找出。
题解：KMP模板
代码：

#include <iostream>
#include <cstring>
#include <string>
#include <vector>
using namespace std;

const int N = 1000002;
int nextt[N];
//string S,T;
vector<int>S,T;
int slen, tlen;

void getNext()
{
    int j, k;
    j = 0; k = -1; nextt[0] = -1;
    while(j < tlen)
        if(k == -1 || T[j] == T[k])
            nextt[++j] = ++k;
        else
            k = nextt[k];

}
/*
返回模式串T在主串S中首次出现的位置
返回的位置是从0开始的。
*/
int KMP_Index()
{
    int i = 0, j = 0,ans=-1;
    getNext();

    while(i < slen && j < tlen)
    {
        if(j == -1 || S[i] == T[j])
        {
            i++; j++;
        }
        else
            j = nextt[j];
		if(j == tlen){
			//ans++;//
			ans=i-j;
			//j=0;//
			break;
		}
    }
    return ans;
}
int main()
{
    
    int TT;
    int i, cc;
    cin>>TT;
    while(TT--)
    {
    	int s1,s2;
    	int temp;
    	cin>>s1>>s2;
    	S.clear();
    	T.clear();
		while(s1--){
    		scanf("%d", &temp); 
    		S.push_back(temp);
		}
		while(s2--){
			scanf("%d", &temp); 
			T.push_back(temp);
		}
        slen = S.size();
        tlen = T.size();
        int ccnt=KMP_Index();
        if(ccnt!=-1)ccnt++;
        cout<<ccnt<<endl;
    }
    return 0;
}