数据结构与算法——二叉搜索树的操作集（C语言）

要求实现给定二叉搜索树的5种常用操作。

函数接口定义：

BinTree Insert( BinTree BST, ElementType X );
BinTree Delete( BinTree BST, ElementType X );
Position Find( BinTree BST, ElementType X );
Position FindMin( BinTree BST );
Position FindMax( BinTree BST );
其中BinTree结构定义如下：

typedef struct TNode *Position;
typedef Position BinTree;
struct TNode{
ElementType Data;
BinTree Left;
BinTree Right;
};
• 函数Insert将X插入二叉搜索树BST并返回结果树的根结点指针；
• 函数Delete将X从二叉搜索树BST中删除，并返回结果树的根结点指针；如果X不• 在树中，则打印一行Not Found并返回原树的根结点指针；
• 函数Find在二叉搜索树BST中找到X，返回该结点的指针；如果找不到则返回空指针；
• 函数FindMin返回二叉搜索树BST中最小元结点的指针；
• 函数FindMax返回二叉搜索树BST中最大元结点的指针。
裁判测试程序样例：

#include <stdio.h>#include <stdlib.h>typedef int ElementType;typedef struct TNode *Position;typedef Position BinTree;struct TNode{    ElementType Data;    BinTree Left;    BinTree Right;};void PreorderTraversal( BinTree BT ); /* 先序遍历，由裁判实现，细节不表 */void InorderTraversal( BinTree BT );  /* 中序遍历，由裁判实现，细节不表 */BinTree Insert( BinTree BST, ElementType X );BinTree Delete( BinTree BST, ElementType X );Position Find( BinTree BST, ElementType X );Position FindMin( BinTree BST );Position FindMax( BinTree BST );int main(){    BinTree BST, MinP, MaxP, Tmp;    ElementType X;    int N, i;    BST = NULL;    scanf("%d", &N);    for ( i=0; i<N; i++ ) {        scanf("%d", &X);        BST = Insert(BST, X);    }    printf("Preorder:"); PreorderTraversal(BST); printf("\n");    MinP = FindMin(BST);    MaxP = FindMax(BST);    scanf("%d", &N);    for( i=0; i<N; i++ ) {        scanf("%d", &X);        Tmp = Find(BST, X);        if (Tmp == NULL) printf("%d is not found\n", X);        else {            printf("%d is found\n", Tmp->Data);            if (Tmp==MinP) printf("%d is the smallest key\n", Tmp->Data);            if (Tmp==MaxP) printf("%d is the largest key\n", Tmp->Data);        }    }    scanf("%d", &N);    for( i=0; i<N; i++ ) {        scanf("%d", &X);        BST = Delete(BST, X);    }    printf("Inorder:"); InorderTraversal(BST); printf("\n");    return 0;}/* 你的代码将被嵌在这里 */

输入样例：

10
5 8 6 2 4 1 0 10 9 7
5
6 3 10 0 5
5
5 7 0 10 3
输出样例：

Preorder: 5 2 1 0 4 8 6 7 10 9
6 is found
3 is not found
10 is found
10 is the largest key
0 is found
0 is the smallest key
5 is found
Not Found
Inorder: 1 2 4 6 8 9

【答案】：

BinTree Insert( BinTree BST, ElementType X ){    if(BST==NULL){         BST =malloc(sizeof(struct TNode));        BST->Data = X;        BST->Left = BST->Right = NULL;    }else if(X<BST->Data)        BST->Left = Insert (BST->Left,X);    else if(X>BST->Data)        BST->Right = Insert(BST->Right,X);    return BST;}BinTree Delete( BinTree BST, ElementType X ){    Position tag;    if(BST == NULL)        printf ("Not Found\n");    else if(X < BST->Data)        BST->Left = Delete(BST->Left,X);    else if(X > BST->Data)        BST->Right = Delete(BST->Right,X);    else if (BST->Left!=NULL && BST->Right!=NULL){        tag = FindMin(BST->Right);        BST->Data = tag->Data;        BST->Right = Delete(BST->Right,BST->Data);    }    else {        tag = BST;        if(BST->Left==NULL)            BST=BST->Right;        else if(BST->Right==NULL)            BST = BST->Left;        free (tag);    }    return BST;}Position Find( BinTree BST, ElementType X ){    while(BST!=NULL){        if(X > BST->Data)            BST = BST->Right;        else if(X < BST->Data)            BST = BST->Left;        else             break;    }    return BST;}Position FindMin( BinTree BST ){    if(BST!=NULL)        while(BST->Left!=NULL)            BST=BST->Left;        return BST;}Position FindMax( BinTree BST ){    if(BST!=NULL)        while(BST->Right!=NULL)            BST=BST->Right;        return BST;} 

【出现过的问题】
1. 被提示a.c: In function 'Delete': a.c:106:8: warning: statement with no effect [-Wunused-value] a.c:107:5: error: expected ';' before 'BST'

原因是

if (......){    ......}else if(......){    ......}//写成了if(....){    .....}else(.....){    ......}

2.将Insert函数中的BST = malloc(sizeof (struct TNode));前面加了类型声明
3.Delete函数中的判断语句if(X > BST->Data)写成了if(X < BST->Data)