此代码原始出处：http://blog.csdn.net/cnyali/article/details/47367403

#include<stdio.h>

#include<string.h>

#include<stdlib.h>

struct node{

	char word[15];

	int count;

	struct node *next[30];

	node(){

		count=0;

		memset(next,0,sizeof(next));

	}

};

void insert(struct node *p,char *s1,char *s2){

	int i,j,k,l=strlen(s1);

	struct node *q;

	for(i=0;i<l;i++){

		k=s1[i]-'a';

		if(p->next[k]==NULL){

			q=new node;

			p->next[k]=q;

		}

		p=p->next[k];

	}

	p->count=1;

	strcpy(p->word,s2);

}

char *find(struct node *p,char *s){

	int i,j,k,l=strlen(s);

	for(i=0;i<l;i++){

		k=s[i]-'a';

		p=p->next[k];

		if(p==0)return NULL;

	}

	if(p->count==1)return p->word;

	else return NULL;

}

int main(){

	freopen("poj2503.in","r",stdin);

	freopen("poj2503.out","w",stdout);

	struct node *h;

	char s[15],s1[15],s2[15];

	int i,j,k,m,n;

	h=new node;

	while(1){

		gets(s);

        if(s[0] == '\0')

            break;

        sscanf(s,"%s %s", s1, s2);

		insert(h,s2,s1);

	}

	while(gets(s)!=NULL){

		if(s[0]=='\0')break;

		char *st=find(h,s);

		if(st!=0)

			puts(st);

		else

			puts("eh");

	}

	return 0;

}