关于二叉排序树 BST

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

 typedef struct node
 {
     double w;
     struct node *l,*r;
 }*Node;

 void Build(Node &rt,double a)//建树
 {
     if(rt==NULL)
     {
         rt=new node;
         rt->w=a;
         rt->l=;
         rt->r=;
     }
     else
     {
         if(a<rt->w)
             Build(rt->l,a);
         else
             Build(rt->r,a);
     }
 }
 double fin(struct node *rt)  //找最小的权
 {
     if(!rt)
         return ;
     else if(!rt->l)
         return rt->w;
     else
         return fin(rt->l);
 }

 void delet(Node &rt,double w)//删除权为w点
 {
     if(!rt)
     {
         printf("没有\n");
         return ;
     }
     else if(rt->w<w)
         delet(rt->r,w);
     else if(rt->w>w)
         delet(rt->l,w);
     else if(rt->l&&rt->r)
     {
         struct node *tmp;
         tmp=rt;
         tmp->w=fin(tmp->r);
         delet(tmp->r,tmp->w);
     }
     else
     {
         struct node *t;
         t=rt;
         if(rt->l)
             rt=rt->l;
         else
             rt=rt->r;
         delete(t);
     }

 }
 void in(struct node *rt) //中序
 {
     if(rt)
     {
         in(rt->l);
         printf("%lf ",rt->w);
         in(rt->r);
     }
     else
         return ;
 }
 double w;
 int aim;

 void search(Node rt,int &cnt) //找第aim小
 {
     if(rt)
     {
         search(rt->l,cnt);
         cnt++;
         if(cnt==aim)
         {
             w=rt->w;
             return;
         }
         search(rt->r,cnt);

     }
 }
 int main()
 {
     int n;
     scanf("%d",&n);
     struct node *root;
     root=;
     for(int i=;i<=n;i++) //插入
     {
         double a;
         scanf("%lf",&a);
         Build(root,a);
     }
     in(root);
     printf("\n");
     scanf("%d",&n);
     for(int i=;i<=n;i++)  //删除
     {
         double a;
         scanf("%lf",&a);
         delet(root,a);
         in(root);
         printf("\n");
     }
     scanf("%d",&n);
     for(int i=;i<=n;i++)
     {
         scanf("%d",&aim);  //第aim小
         int cnt=;
         search(root,cnt);
         printf("%lf\n",w);
     }
     return ;
 }
 /*
 9
 3 4 2 5 7 6 3.5 3.1 3.6
 0
 3
 6
 7
 3

 */