基本二叉搜索树的第K小元素

 #include<stdio.h>
 #include<stdlib.h>
 typedef struct node *btlink;
 struct node
 {
     int data;
     btlink left;
     btlink right;
     int t;
 };

 btlink BT;
 void insert(btlink q, int x)
 {
     btlink p = (btlink)malloc(sizeof(node));
     p->data = x;
     p->left = NULL;
     p->right = NULL;
     p->t=;
     if(q == NULL)
     {
         BT = p;
         //printf("BT=%d\n",BT->t);
         return ;
     }
     while(q->left!=p&&q->right!=p)
     {
         if(x<q->data)
         {
             if(q->left)
             {
                 q->t++;
                 q = q->left;
             }
             else
             {
                 q->t++;
                 q->left = p;
             }
         }
         else
         {
             if(q->right)
             {
                 q = q->right;
             }
             else
             {
                 q->right = p;
             }
         }
     }
     return;
 }
 void InOrder(btlink root,int k)
 {

     while(k!=root->t+)
     {
         //printf("k=%d t=%d\n",k,root->t);
         if(k>root->t+)
         {
             k=k-root->t-;
             root=root->right;
         }
         else
         {

             root=root->left;
         }
     }
     printf("%d\n",root->data);
 }

 int main()
 {
     int n,i,index=,x;
     char a[];
     scanf("%d",&n);
     BT=(btlink)malloc(sizeof(node));
     BT=NULL;
     for(i=;i<n;i++)
     {
         scanf("%s",a);
         if(a[]=='a')
         {
             scanf("%d",&x);
             insert(BT,x);
         }
         else if(a[]=='p')
         {

             index++;
             InOrder(BT,index);
         }
     }
     return ;
 }