SDUTOJ 2482 二叉排序樹

#include<iostream>
#include<string.h>
using namespace std;
char c[100],d[100];
int o=0,e=0;
typedef struct bitnode
{
	char data;
	struct bitnode *lchild,*rchild;
}bitnode,*bitree;
void insert(bitree &t1,char key)
{
	if(t1==NULL)
	{
		t1=new bitnode;
		t1->lchild=t1->rchild=NULL;
		t1->data=key;
		return ;
	}
	else
	{
		if(key<t1->data)
			insert(t1->lchild,key);
		else 
			insert(t1->rchild,key);
	}
}
void preorder(bitree t)
{
	if(t!=NULL)
	{
		c[o++]=t->data;
		preorder(t->lchild);
		preorder(t->rchild);
	}
}
void postorder(bitree t3)
{
	if(t3!=NULL)
	{
        postorder(t3->lchild);
		postorder(t3->rchild);
		d[e++]=t3->data;
	}
}
int main()
{
	char a[100],b[100];
	int n,len,i;
	bitree t1;
	while(cin>>n)
	{
		if(n==0)
		{
			break;
		}
		t1=NULL;
		cin>>a;
		len=strlen(a);
		for(i=0;i<len;i++)
		{
			insert(t1,a[i]);
		}
		preorder(t1);
		c[o]='\0';
		postorder(t1);
		d[e]='\0';
		for(i=0;i<n;i++)
		{
			cin>>b;
			if(strcmp(a,b)==0)
				cout<<"YES"<<endl;
			else if(strcmp(b,c)==0)
				cout<<"YES"<<endl;
			else if(strcmp(b,d)==0)
				cout<<"YES"<<endl;
			else
				cout<<"NO"<<endl;
		}
	}
	return 0;	
}