KMP算法求模式串在原串中出现的次数

#include <iostream>
#include <cstring>
#include <stdio.h>
#include <stdlib.h>
#include <iomanip>
#include <algorithm>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <cmath>
using namespace std;
#define INF 0x3f3f3f3f
#define maxn 110000
const double PI = acos(-1.0);
typedef long long ll;

int Next[maxn];

char a[1000];

void get_next(char a[]);
int KMP(char a[], char b[]);

int main()
{
    char b[maxn] ;
    char a[maxn];
    while(cin >> a >> b)
    {
        int sum = KMP(a, b);
        cout << sum << endl;
    }
    return 0;
}

void get_next(char a[])
{
    int i = 0, j = -1;
    Next[0] = -1;
    while(a[i] != '\0')
    {
        if(j == -1 || a[i] == a[j])
        {
            i++;
            j++;
            Next[i] = j;
        }
        else j = Next[j];
    }
}
int KMP(char a[], char b[])
{
    get_next(b);
    int sum = 0;
    int lena = strlen(a);
    int lenb = strlen(b);
    int i = 0, j = 0;
    while(i < lena && j < lenb)
    {
        if(j == -1 || a[i] == b[j])
        {
            ++i;
            ++j;
            //此处开始与KMP常规算法不同,以此为找到模式串的标志并尽心回溯
            if(j == lenb)
            {
                sum++;
                j = Next[j];
            }
        }
        else
            j = Next[j];

     }
    return sum;
}
    原文作者:KMP算法
    原文地址: https://blog.csdn.net/m0_38081836/article/details/78137453
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