struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
void preorder(struct list *t)//t为根节点的指针
{
  if(t!=NULL)
  {
    printf("%d,",t->a);
    preorder(t->left);
    perorder(t->right);
  }
}

struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
void preorder(struct list *t)//t为根节点的指针
{
  if(t!=NULL)
  {
    preorder(t->left);
    printf("%d,",t->a);
    perorder(t->right);
  }
}

struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
void preorder(struct list *t)//t为根节点的指针
{
  if(t!=NULL)
  {
    preorder(t->left);
    perorder(t->right);
    printf("%d,",t->a);
  }
}

struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
struct list * search(struct list *t,int k)
{
  if(t==NULL||t->a==k)
    return t;
  if(t->a<k)
    search(t->right);
  else
    search(t>left);
};

struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
struct list * search(struct list *t,int k)
{
  while(true)
  {
    if(t==NULL||t->a==k)
    {
      return t;
      break;
    }
    if(t->a<k)
      t=t->rigth;
    else
      t=t->left;

  }
};

{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
struct lsit *max_tree(struct lsit *t)
{
  while(t!=NULL)
  {
    t=t->right;
  }
  return t;
};

struct list
{
  struct list *left;//左子树
  struct list *right;//右子树
  int a;//结点的值
};
void insert(struct list *root,struct list * k)
{
  struct list *y,*x;
  x=root;
  while(x!=NULL)
  {
    y=x;
    if(k->a<x->a)
    {
      x=x->left;
    }
    else
      x=x->right;
  }
  if(y==NULL)
    root=k;
  else if(k->a<y->a)
    y->left=k;
  else
    y->right=k;

}