kmp 练习下

/* * ===================================================================================== * *       Filename:  kmp.cpp * *    Description:   * *        Version:  1.0 *        Created:  10/14/2012 07:38:59 PM *       Revision:  none *       Compiler:  gcc * *         Author:  lsff (lsff),  *   Organization:   * * ===================================================================================== */#include <stdlib.h>#include <iostream>#include <stdio.h>#include <string.h>using namespace std;void getNext(int *next,char *tr,int n){int i,j;i=j=0;next[i]=-1;while(i<n){if(j==-1||tr[i]==tr[j]){++i;++j;if(tr[i]!=tr[j])  next[i]=j;else   next[i]=next[j];}else   j=next[j];}}int getPos(char *src,char *pat,int *next){if(!src||!pat)  return -1;int slen=strlen(src);int plen=strlen(pat);next=new int[plen];getNext(next,pat,plen);int i=0,j=0;while(i<slen&&j<plen){if(src[i]==pat[j]){++i;++j;}else {if(j==0) i++;else   j=next[j-1]+1;}}return j==plen? i-plen :-1;}#define maxn 1024int main(){char src[maxn],pat[maxn],c;bzero(src,sizeof(src));bzero(pat,sizeof(pat));int i;i=0;while((c=getchar())!='\n') src[i++]=c;if(c!='\n') while(getchar()!='\n');i=0;while((c=getchar())!='\n') pat[i++]=c;if(c!='\n') while(getchar()!='\n');int *next;int index=getPos(src,pat,next);cout<<index<<endl;}