Oulipo（KMP） POJ - 3461

给出n对字符串，p,s；想要知道p在s中出现了几次。

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#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<cstring>
#include<stdio.h>
#include<algorithm>
#include<map>
#include<queue>
#include<set>
#include <sstream>
#include<vector>
#include<cmath>    
#include<stack>
#include<time.h>
#include<ctime>
using namespace std;
#define inf 1<<30
#define eps 1e-7
#define LD long double
#define LL long long
#define maxn 1000005    
int Next[maxn] = {};
void GetNext(string s)//套上模板
{
    int i = 0;
    int j = -1;
    int len = s.length();
    Next[0] = -1;
    while (i < len)
    {
        if (j == -1 || s[i] == s[j])
        {
            i++;
            j++;
            Next[i] = j;
        }
        else
        {
            j = Next[j];
        }
    }
}
int Kmp(string p, string s)
{
    GetNext(s);//找出s的next数组
    int i = 0;
    int j = 0;
    int len1 = p.length();
    int len2 = s.length();
    int sum = 0;
    while (i < len1)
    {
        if (j == -1 || p[i] == s[j])
        {
            i++;
            j++;
        }
        else
        {
            j = Next[j];
        }
        if (j == len2)//找到一个
        {
            sum++;//加一
            j = Next[j];
        }
    }
    return sum;
}
int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        string s, p;
        cin >> s >> p;
        printf("%d\n", Kmp(p, s));
    }
}

 

 

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