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 110000const 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;}