树：二叉排序树

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

typedef struct tree
{
    int  data;
    struct tree *l,*r;
} tree;

tree *BST(tree *t,int k)
{
    if(t==NULL)
    {
        t=(tree *)malloc(sizeof(tree));//应该放在这边
        t->data=k;
        t->r=t->l=NULL;
    }
    else
    {
        if(k<t->data)
            t->l=BST(t->l,k);
        else
            t->r=BST(t->r,k);
    }
    return t;
}

tree *creat(tree *t,int a[],int n)
{
    t=NULL;
    int i;
    for(i=0; i<n; i++)
        t=BST(t,a[i]);
    return t;
}

int compare(tree *t1,tree *t2)
{
    if(!t1&&!t2)
        return 1;
    else if(t1&&t2)
    {
        if(t1->data!=t2->data)
        return 0;
        else if(compare(t1->l,t2->l)&&compare(t1->r,t2->r))
            return 1;
        else
            return 0;
    }
    else
        return 0;
}

int main()
{
    tree *t1,*t2;
    int n,b[15],i;
    char a[15];
    while(~scanf("%d",&n)&&n)
    {
        scanf("%s",a);
        int l;
        l=strlen(a);
        for(i=0; i<l; i++)
            b[i]=a[i]-'0';
        t1=creat(t1,b,l);
        while(n--)
        {
            scanf("%s",a);
            l=strlen(a);
            for(i=0; i<l; i++)
                b[i]=a[i]-'0';
            t2=creat(t2,b,l);
            int t=compare(t1,t2);
            if(t)
                printf("YES\n");
            else
                printf("NO\n");
        }
    }
return 0;
}