迷失の搜索树

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int k, a[1001];
struct node
{
    int data;
    struct node *lc;
    struct node *rc;
};
struct node *creat(struct node *root, int x)
{
    if(root == NULL)
    {
        root = (struct node *)malloc(sizeof(struct node));
        root->lc = NULL;
        root->rc = NULL;
        root->data = x;
    }
    else
    {
        if(x > root->data)
        {
            root->rc = creat(root->rc, x);
        }
        else
        {
            root->lc = creat(root->lc, x);
        }
    }
    return root;
};
void houxu(struct node *root)
{
    if(root != 0)
    {
        houxu(root->lc);
        houxu(root->rc);
        a[k++] = root->data;
    }
}
int main()
{
    int n, i, x;
    struct node *root;
    while(scanf("%d", &n) != EOF)
    {
        root = NULL;
        k = 0;
        for(i = 1; i <= n; i++)
        {
            scanf("%d", &x);
            root = creat(root, x);
        }
        houxu(root);
        for(i = 0; i < k; i++)
        {
            if(i == k - 1)
            {
                printf("%d\n", a[i]);
            }
            else
            {
                printf("%d ", a[i]);
            }
        }
    }
    return 0;
}