KMP算法代码案例

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

int *computer_prefix(char *str_p,int *tt){

if(NULL == str_p)
return NULL;
int i=0,j=0;
int m = strlen(str_p);

tt[0]=0;
for(i=1;i<m;i++){
while(j>0 && str_p[j]!=str_p[i])
j=tt[j];

if(str_p[j]==str_p[i])
j=j+1;
tt[i]=j;
}
return tt;
}

int kmp_matcher(char *str_t,char *str_p){
if(NULL ==str_t || NULL == str_p)
return -1;

int flag = -1;
int n = strlen(str_t);
int m = strlen(str_p);
int i=0,j=0;
int *tt = (int*)malloc(sizeof(int)*m);
computer_prefix(str_p,tt);

if(NULL == tt)
return -1;

//printf tt
for(i=0;i<m;i++){
printf("tt[%d]=%d ",i,tt[i]);
}
printf("\n");

for(i=0;i<n;i++){
while(j>0 && str_t[i] != str_p[j])
j = tt[j-1];

if(str_t[i] == str_p[j])
j++;
if(j == m){
flag++;
printf("positon:%d\n",i-j+1);
j = tt[j-1];
}
}
free(tt);
tt = NULL;
return flag;
}

void main(){
char *str_p="ababaca";
char *str_t="aababacaafababaca";
printf("orgin_str:%s\n",str_t);
printf("find_str:%s\n",str_p);
int find_num = kmp_matcher(str_t,str_p);
printf("find %d locations\n",find_num+1);
}