hihoCoder 1015 KMP算法

题意：经典字符串匹配算法。给定原串和模式串，求模式串在原串中出现的次数。算法讲解

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AC代码

#include <cstdio>
#include <cmath>
#include <cctype>
#include <bitset>
#include <algorithm>
#include <cstring>
#include <utility>
#include <string>
#include <iostream>
#include <map>
#include <set>
#include <vector>
#include <queue>
#include <stack>
using namespace std;
#pragma comment(linker, "/STACK:1024000000,1024000000")
#define eps 1e-10
#define inf 0x3f3f3f3f
#define PI pair<int, int>
typedef long long LL;
const int maxn = 1e4 + 5;
char T[maxn*100], p[maxn];
int nex[maxn];
void getNext(char *P, int *nex, int len) {
    nex[0]= -1;
    for(int i = 1; i < len; ++i)    {
        int j = nex[i-1];
        while(j >= 0 && p[j+1] != p[i]) j = nex[j];
        if(p[j+1] == p[i]) nex[i] = j+1;
        else nex[i] = -1;
    }
}
//统计模式串出现的次数
int KMP(char *T, char *p, int *nex) {
    int n = strlen(T), m = strlen(p);
    getNext(p, nex, m);
    int j = -1, cnt = 0;
    for(int i = 0; i < n; ++i) {
        while(j >= 0 && T[i] != p[j+1]) j = nex[j];
        if(T[i] == p[j+1]) j++;
        if(j == m-1) {
            cnt++;
            j = nex[j];
        }
    }
    return cnt;
}
int main() {
    int n;
    scanf("%d", &n);
    while(n--) {
        scanf("%s%s", p, T);
        printf("%d\n", KMP(T, p, nex));
    }
    return 0;
} 

如有不当之处欢迎指出！