老司机不多说，直接上代码

头文件：

#ifndef BINARYTREE_FIND_H_INCLUDED
#define BINARYTREE_FIND_H_INCLUDED

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 // BINARYTREE_FIND_H_INCLUDED

实现：

#include "BinaryTree_Find.h"
#include <stdio.h>
#include <stdlib.h>
struct TreeNode
{
    ElementType Element;
    SearchTree Left;
    SearchTree Right;
};
void FatalError(char * s)
{
    printf("%s\n",s);
}

void Error(char * s)
{
    printf("%s\n",s);
}
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)
    {
        T = malloc(sizeof (struct TreeNode));
        if(T == NULL)
            FatalError("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);
    return T;
}

SearchTree Delete(ElementType X,SearchTree T)
{
    Position TmpCell;
    if(T == NULL)
        Error("Element not found");
    else if(X < T->Element)
        T->Left = Delete(X,T->Left);
    else if(X > T->Element)
        T->Right = Delete(X,T->Right);
    else if(T->Left && T->Right)
    {
        TmpCell = FindMin(T->Right);
        T->Element = TmpCell->Element;
        T->Right = Delete(T->Element,T->Right);
    }
    else
    {
        TmpCell = T;
        if(T->Left == NULL)
            T = T->Right;
        else if(T->Right == NULL)
            T = T->Left;
        free(TmpCell);
    }

    return T;
}
int main()
{
    SearchTree T = malloc(sizeof(struct TreeNode));
    T->Element = 100;
    T->Left = NULL;
    T->Right = NULL;
    int i;
    for(i = 0; i < 50; i++)
        Insert(i,T);
    //Delete(0,T);
    Position MIN = FindMin(T);
    Position MAX = FindMax(T);
    printf("%d\n",MIN->Element);
    printf("%d\n",MAX->Element);
    free(T);
    return 0;
}

代码改编自：《数据结构与算法分析》第二版