KMP算法之next数组分析

不知道怎么插入公式，直接贴图了。。。

附上源代码如下，错误之处，望请指正！

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void get_next_value(char *str, int len, int *next_value){
	int i = 1, j = 0;
	next_value[0] = 0;
	while(i < len){
		if(str[i] != str[j]){
			next_value[i] = j;
			while(j && str[i] != str[j]){
				j = next_value[j];
			}	
		}
		else{
			next_value[i] = next_value[j];
			j++;
		}
		i++;
	}
}


int kmp_search(char *str, int slen, char *pstr, int plen, int *next_value){
	int si = 0, pi = 0;
	if(plen > slen) return -1;
	while(si < slen){
		if(str[si] == pstr[pi]){
			si++, pi++;
			if(pi == plen){
				return si - plen;
			}
		}
		else{
			if(pi == 0){
				si++;
			}
			else
				pi = next_value[pi];
		}
	}
	return 0;
}

int main(int argc, char **argv){
	if(argc < 3){
		printf("usage: *.exe pattern string\n");
		return -1;
	}

	char *pattern = argv[1];
	char *string = argv[2];
	int *next_value = (int*)malloc(4 * strlen(pattern));
	int off;
	get_next_value(pattern, strlen(pattern), next_value);
	printf("\n");
	off = kmp_search(string, strlen(string), pattern, strlen(pattern), next_value);
	printf("%s\n", string + off);
	free(next_value);
	return 0;
}