Horspool算法的C++实现

#include<iostream>
using namespace std;

const int HASH_SIZE=256;
int table[HASH_SIZE];                                  //存放查找文本的信息

void ShiftTable(char pattern[]) {

	int m=strlen(pattern);		
	for(int i=0;i<HASH_SIZE;i++)		//table所有元素初始化为m
		 table[i]=m;
	for(int j=0;j<m-1;j++)
		table[ pattern[j] ]=m-1-j;

}

int HorspoolMatching(char  pattern[],char  text[]) {      //pattern为模式串;text为查找字符串

	ShiftTable(pattern);
	int m=strlen(pattern);
	int n=strlen(text);
	int i=m-1;					   //模式最右端位置
	while(i <= n-1){
		int k=0;                   //匹配字符的个数
		while(k<=m-1 && pattern[m-1-k] == text[i-k] )
			 k++;
		if(k==m)
			 return i-m+1;
		else
		  i=i+table[ text[i] ];	   //
	}

	return -1;
}


int main() {
       char p[20]={"China"};
       char t[1000]={"People's Republic of China,Welcome!"};
       int    pos = HorspoolMatching(p,t);
       cout<<"\n"<<pos<<endl;
       return 0;
}
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