带有父节点的二叉查找树实现

看来得要个父节点，因为后面的红黑树很需要啊！！

#include <iostream>
using namespace std;
struct tree
{
    int data;
    tree *left,*right,*parent;
};
void tree_insert(tree *&, int);
//二叉查找树的初始化构建
void tree_init(tree *&T)
{
    cout << "please input numbers of tree until the input is invalid" << endl;
    int data = 0;
    while (cin >> data)
    {
         tree_insert(T, data);
    }
}
//插入
void tree_insert(tree * &T,int value)
{
   if (T == NULL)
   {
       T = new tree();
       T->data = value;
       T->left = T->right = T->parent = NULL;
   } 
   else
   {
       if (T->data > value)
       {
           tree_insert(T->left, value);
           if (T->left)
              T->left->parent = T;
       }
       else
       {
           tree_insert(T->right, value);
           if (T->right)
               T->right->parent = T;
       }
   }
}
//preorder to print the data of the whole tree 
void tree_print1(tree *T)
{
   if (T != NULL)
   {
       tree_print1(T->left);
       cout << T->data << " ";
       tree_print1(T->right);
   }
}
//中序遍历
void tree_print2(tree *T)
{
   if (T != NULL)
   {
       tree_print2(T->right);
       cout << T->data << " " ;
       tree_print2(T->left);
   }
}
//后序遍历
void tree_print3(tree *T)
{
    if (T != NULL)
    {
        cout << T->data << " ";
        tree_print3(T->left);
        tree_print3(T->right);
    }
}
//find a value in the tree with the method of recursion 
bool tree_search(tree *T, int value)
{
    tree *t = T;
    while (t != NULL)
    {
        if (t->data == value)
        {
            return true;
        }
        if(t->data < value)
            t = t->right;
        else
            t = t->left;
    }
    return false;
}
//求最小值
tree * tree_mininum(tree *T)
{
   while (T && T->left)
   {
       T = T->left;
   }
   return T;
}
//求后继结点
tree *tree_successor(tree *T)
{
    if (!T->right)
    {
        return tree_mininum(T->right);
    }
    tree *y = T->parent;
    while(y && T == y->right)
    {
        T = y;
        y = y->parent;
    }
    return y;
}
//删除节点，不考虑性质
void del1(tree *&t)
{
    if (t == t->parent->left)
    {
        if(!t->left && !t->right)
          t->parent->left = NULL;
        if(t->left != NULL)
          t->parent->left = t->left;
        if(t->right != NULL)
          t->parent->left = t->right;
    } 
    else
    {
        if(!t->left && !t->right)
            t->parent->right = NULL;
        if(t->left != NULL)
            t->parent->right= t->left;
        if(t->right != NULL)
            t->parent->right = t->right;
    }
}
//删除任意节点，并保持二叉查找树的性质
void tree_del(tree *T)
{
   tree *y = NULL;
   if (T->left == NULL || T->right == NULL)
   {
       y = T;
       del1(T);
   }
   else
   {
       y = tree_successor(T);
       T->data = y->data;
       del1(y);
   }

}

int main()
{
   tree *T = NULL;
   tree_init(T);
       cout << "The number in the tree is :" << endl;
   tree_print1(T);
   cout << endl;
   tree_print2(T);
   cout << endl;
   tree_print3(T);
   int find_value = 0;
   //cout << endl << "please input the number you want to find" <<endl;
   cin.clear();
   //cin >> find_value;
   //cout  << tree_search(T,find_value) << endl;
   int del_data = 0;
   cin >> del_data;
   tree_del(T);
}