【KMP求字串匹配次數】 hdu 1686

Hdu 1686

求模式串出現在目標串的次數

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<stack>
#include<queue>
#include<deque>
#include<map>
#include<algorithm>
using namespace std;
typedef long long LL;
//#pragma comment(linker, "/STACK:102400000,102400000")

/*
hdu 1686 KMP簡單題
求模式串出現在目標串的次數
*/
const double PI = acos(-1.0);
const double eps = 1e-6;
const int INF=0x3f3f3f3f;
const int mod = 1e9+7;
const int N=1000010;

char s[N],p[N];
int net[N];
void getnext(int len)
{
    int k = -1;
    net[0] = -1;
    for(int i = 1; i < len; i++)
    {
        while(k!=-1 && p[k+1]!=p[i])
            k = net[k];
        if(p[k+1]==p[i])
            k++;
        net[i] = k;
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%s%s",p,s);
        int lenp = strlen(p);
        getnext(lenp);
        int lens = strlen(s);
        int k = -1;
        int num = 0;
        for(int i = 0; i < lens; i++)
        {
            while(k!=-1 && p[k+1]!=s[i])
                k = net[k];
            if(p[k+1]==s[i])
                k++;
            if(k==lenp-1)
            {
                k = net[k];
                num++;
            }
        }
        printf("%d\n",num);
    }
    return 0;
}