KMP算法代码实现

#include <iostream>
#include <cstring>
using namespace std;
void getNext(const char *p, int next[]);
int KmpSearch(const char *s, const char *p, int next[]);
// 手刃KMP
int main(void){
    const char *s = "aabaabaaf";
    const char *p = "aabaaf";
    int next[strlen(p)];
    getNext(p, next);
    int result = KmpSearch(s, p, next);
    if (result != -1)
    {
        /* code */
        cout<<"结果为"<<result + 1<<endl;
    }
    else
        cout<<"找不到相同的字符串！"<<endl;
    
    return 0;
}

void getNext(const char *p, int next[])
{
    int j = 0;
    next[0] = 0;
    for (int i = 1; i < strlen(p); i++)
    {
        while (j > 0 && p[i] != p[j])
        {
            j = next[j - 1];
            /* code */
        }
        if (p[i] == p[j])
        {
            /* code */
            j++;
        }
        next[i] = j;   
    }
}
int KmpSearch(const char *s, const char *p, int next[]){
    int i = 0;
    int j = 0;
    int len_s = strlen(s);
    int len_p = strlen(p);
    while (i < len_s && j < len_p)
    {
        /* code */
        if (j == 0 || s[i] == p[j])
        {
            i++;j++;
        }
        else
            j = next[j - 1];
    }
    if (j >= len_p)
    {
        return (i - len_p);
    }
    else return -1;
}