字符串匹配之kmp

/*
file:KMP_alogrithm.c
brief:
auther:yejing
data:2014.07.26
ver:1(create the file 7/26)
test pc:ubuntu 12.14
*/

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


 
void generate_bt_array(int bt_array[], char tar_string[], int n)
{
    int i = 1;
    bt_array[0] = 0;
    while(i < n)
    {
        if(tar_string[i] == tar_string[bt_array[i-1]])
            bt_array[i] = bt_array[i-1] + 1;
        else
            bt_array[i] = 0;

	++i;
    }
	return;
}
 
int kmp_alogrithm(char* src_string, char* tar_string)
{
	if(!src_string || !tar_string)
		return -1;

    int i = 0, j = 0;
	
    int tar_len = strlen(tar_string);
    int src_len = strlen(src_string);
    
    int* bt_array = (int*)malloc(sizeof(int) * tar_len);
	
    if(!bt_array)
	return -1;
		
    generate_bt_array(bt_array, tar_string, tar_len);
 
    while( i < src_len && j < tar_len)
    {
        if(src_string[i] == tar_string[j])
        {
            ++i;
            ++j;
        }
        else
        {
            if(!j)
                ++i;
            else
		j = bt_array[j - 1];
        }
   }
   
    free(bt_array);
 
    if(j==tar_len)
        return i-tar_len;
    else
        return -1;
}

int main(int argc, char* argv[])
{
    char *src_string = "ABCDABCDABCDABCDABCDABCDABCDABFABCDABE";
    char *tar_string = "ABCDABE";
	 
    int index = kmp_alogrithm(src_string, tar_string);
    printf("kmp_index:%d \n", index);
	
    pause();
    return 0;
}