二叉排序树问题

#include <stdio.h>
#include <malloc.h>

typedef struct node
{
    int key;
    struct node *lchild, *rchild;
}*bilist, binode;

bilist Insert (bilist t, binode *s)
{
    binode *p, *q;

    if (t==NULL)
        return s;

    p = t;
    while (p!=NULL)
    {
        q = p;            //q结点为p结点的双亲
        if (s->key==p->key)
            return t;
        else if (s->key > p->key)
            p = p->rchild;
        else
            p = p->lchild;
    }

    if (s->key > q->key)
        q->rchild = s;
    else
        q->lchild = s;

    return t;
}

bilist CreateBST (bilist t)
{
    binode *s;
    int i, n;
    int key;

    t = NULL;
    printf ("结点数：");
    scanf ("%d", &n);
    printf ("输入%d个结点的编号：", n);
    for (i=1; i<=n; i++)
    {
        scanf ("%d", &key);
        s = (binode*) malloc (sizeof(binode));
        s->lchild = NULL;
        s->rchild = NULL;
        s->key = key;
        t = Insert (t, s);
    }
    return t;
}

void InorderBST (bilist t)
{
    binode *s;

    s = t;
    if (s!=NULL)
    {
        InorderBST (s->lchild);
        printf ("%d ", s->key);
        InorderBST (s->rchild);
    }
}

void InsertBST (bilist t, int k)
{
    binode *p, *f;

    p = t;
    while (p)
    {
        if (p->key==k)
            return;
        f = p;
        p = (k < p->key) ? p->lchild : p->rchild;
    }

    p = (binode*) malloc (sizeof(binode));
    p->key = k;
    p->lchild = p->rchild = NULL;

    if (t==NULL)        //若t为空则直接插入
        t = p;

    else if (k < f->key)
        f->lchild = p;

    else
        f->rchild = p;
}

void FreeBST (bilist t)
{
    if (t->lchild)
        FreeBST (t->lchild);
    if (t->rchild)
        FreeBST (t->rchild);
    free (t);
}

void main ()
{

    int pa, i;
    char ch;
    bilist T;

    T = CreateBST (T);
    printf ("二叉查找树的中序遍历为：");
    InorderBST (T);
    printf ("\n");
   
    printf ("是否插入关键字？(Y/N)");
    ch = getchar ();                //这句运行不了
    while (ch=='Y' || ch=='y')
    {
        printf ("请输入关键字：");
        scanf ("%d", &pa);
        InsertBST (T, pa);
        printf ("是否继续插入关键字？(Y/N)");
        ch = getchar ();
    }

    printf ("新二叉查找树的中序遍历为：");
    InorderBST (T);
    printf ("\n");
    FreeBST (T);

}