/*Tree.h*/
#ifndef _Tree_H

struct TreeNode;
typedef struct TreeNode *Position;
typedef struct TreeNode *SearchTree;
typedef int ElementType;

SearchTree MakeEmpty(SearchTree T);
Position Find(ElementType X, SearchTree T);
Position FindMin(SearchTree T);
Position FindMax(SearchTree T);
SearchTree Insert(ElementType X, SearchTree T);
SearchTree Delete(ElementType X, SearchTree T);
ElementType Retrieve(Position P);

#endif // !_Tree_H

/*Tree.cpp*/
#include<stdio.h>
#include<stdlib.h>
#include"Tree.h"

struct TreeNode
{
    ElementType Element;
    SearchTree Left;
    SearchTree Right;
};

SearchTree MakeEmpty(SearchTree T)
{
    if (T != NULL)
    {
        MakeEmpty(T->Left);
        MakeEmpty(T->Right);
        free(T);
    }
    return NULL;
}

Position Find(ElementType X, SearchTree T)
{
    if (T == NULL)
        return NULL;
    if (X < T->Element)
        return Find(X, T->Left);
    else if (X > T->Element)
        return Find(X, T->Right);
    else
        return T;
}

Position FindMin(SearchTree T)
{
    if (T == NULL)
        return NULL;
    else if (T->Left == NULL)
        return T;
    else
        return FindMin(T->Left);
}

Position FindMax(SearchTree T)
{
    if (T != NULL)
        while (T->Right != NULL)
            T = T->Right;
    return T;
}

SearchTree Insert(ElementType X, SearchTree T)
{
    if (T == NULL)
    {
        /*Creat and return a one-node tree*/
        T = (TreeNode*)malloc(sizeof(struct TreeNode));
        if (T = NULL)
            printf("Out of space!");
        else
        {
            T->Element = X;
            T->Left = T->Right = NULL;
        }
    }
    else if (X < T->Element)
        T->Left = Insert(X, T->Left);
    else if (X > T->Element)
        T->Right = Insert(X, T->Right);
    /*else X is in the tree already;we'll do nothing*/

    return T;
}
SearchTree Delete(ElementType X, SearchTree T)
{
    Position TmpCell;
    if (T = NULL)
        printf("Element not found!");
    else if (X > T->Element)/*Go left*/
        T->Left = Delete(X, T->Left);
    else if (X < T->Element)/*Go right*/
        T->Right = Delete(X, T->Right);
    /*Found element to be deleted*/
    else if (T->Left&&T->Right)/*Two children*/
    {
        /*Repalce with smallest in right subtree*/
        TmpCell = FindMin(T->Right);
        T->Element = TmpCell->Element;
        T->Right = Delete(T->Element, T->Right);
    }
    else /*One or zero children*/
    {
        TmpCell = T;
        if (T->Left = NULL)/*Aslo handles 0 child*/
            T = T->Right;
        else if (T->Right = NULL)
            T = T->Left;
        free(TmpCell);
    }
    return T;
}

int main()
{
    SearchTree T{} ;
    Insert(1, T);
    Insert(2, T);
    Insert(3, T);
    Insert(4, T);
    Insert(5, T);
    Insert(6, T);
    Insert(8, T);
    printf("%d", FindMin(T)->Element);
    printf("%d", FindMax(T)->Element);
    printf("%d", Find(4, T)->Element);
    Delete(4, T);
    Find(4, T);
    MakeEmpty(T);
    return 0;
}