kmp模式匹配模板

kmp算法的关键就是前缀和后缀

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
using namespace std;
const int MAX_LEN = 1e5 + 10;

int n, len1, len2;
char t[MAX_LEN], p[MAX_LEN];
int _next[MAX_LEN];
inline void get_next()
{
   
    int i = 0, j;
    _next[0] = j = -1;
    while (i < len2) {
   
        if (j < 0 || p[i] == p[j]) {
   
            ++i; ++j;
            _next[i] = j;
        }
        else {
   
            j = _next[j];
        }
    }
}
void kmp() 
{
   
    int i = 0, j = 0;
    while (i < len1) {
   
        if (j < 0 || t[i] == p[j]) {
   
            i++; j++;
        }
        else {
   
            j = _next[j];
        }
        if (j == len2) {
   
            printf("匹配成功");
        }
    }
}