#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MaxSize 100
/*构造match数组*/
void BuildMatch(char *pattern,int *match)
{
int n = strlen(pattern);
int dis = 1,s = 0;
while (s+dis < n)
{
if(pattern[s] == pattern[s+dis])
{
match[s+dis] = match[s+dis-1]+1;
s++;
}
else
{s = 0;dis++;}
}
}
/*KMP*/
int KMP(char *str,char *pattern)
{
int n = strlen(str);
int m = strlen(pattern);
int s = 0,p = 0;
int *match = (int*)malloc(sizeof(int)*m);
memset(match,-1,sizeof(int)*n);
BuildMatch(pattern,match);
while (s < n && p < m)
{
if(str[s] == pattern[p]){s++;p++;}
else if(p > 0)p = match[p-1]+1;
else s++;
}
return p == m ? s-m+1: -1;
}
int main(int argc, char const *argv[]) {
char str[MaxSize],pattern[MaxSize];
printf("请输入字符串:\n");
scanf("%s",str);
printf("请输入子串:\n");
scanf("%s",pattern);
int result = KMP(str,pattern);
if(result == -1)printf("查找失败\n");
else printf("首字母位置为:%d\n",result);
return 0;
}
王道考研 ++++ KMP算法
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转载自blog.csdn.net/WX_1218639030/article/details/100070620
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