二叉树--C语言实现

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数据结构与算法分析 笔记

searchtree.c
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#include <stdio.h>;
#include <stdlib.h>;
#define FatalError(str) fprintf(stderr, "%s\n", str),exit(1);
#define Error(str) FatalError(str);

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);
Position FindMax(SearchTree);
SearchTree Insert(ElementType X, SearchTree T);
SearchTree Delete(ElementType X, SearchTree T);
ElementType Retrieve(Position P);
ElementType DeleteMin(SearchTree T);

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

SearchTree MakeEmpty(SearchTree T)
{
    if(T != NULL){
        T-&gt;Element = NULL;
        MakeEmpty(T-&gt;Left);
        MakeEmpty(T-&gt;Right);
    }
    return NULL;
}

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

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

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

// Position FindMax(SearchTree T)
// {
//     if(T == NULL){
//         return NULL;
//     }else
//     if(T-&gt;Right == NULL){
//         return T;
//     }else{
//         return FindMax(T-&gt;Right);
//     }
// }

SearchTree Insert(ElementType X, SearchTree T)
{
    if(T == NULL)
    {
        T = malloc(sizeof(struct TreeNode));
        if( T == NULL)
        {
            FatalError("Out of space!!!");
        }
        else
        {
            T-&gt;Element = X;
            T-&gt;Left = T-&gt;Right = NULL;
        }
    }
    else
    if(X &lt; T-&gt;Element)
    {
        T-&gt;Left = Insert(X, T-&gt;Left);
    }
    else
    if(X &gt; T-&gt;Element)
        T-&gt;Right = Insert(X, T-&gt;Right);
    return T;
}

ElementType Retrieve(Position P)
{
    return P-&gt;Element;
}

SearchTree Delete(ElementType X, SearchTree T)
{
    Position P;
    if(T == NULL)
    {
        Error("Element not found");
    }
    else 
    if(X &lt; T-&gt;Element)
    {
        T = T-&gt;Left;
        return Delete(X, T);
    }
    else 
    if(X &gt; T-&gt;Element)
    {
        T = T-&gt;Right;
        return Delete(X, T);
    }
    else
    if(T-&gt;Left &amp;&amp; T-&gt;Right)
    {
        T-&gt;Element = DeleteMin(T-&gt;Right);
    }
    else
    {
        P = T;
        if(T-&gt;Left == NULL)
            T = T-&gt;Right;
        else
        if(T-&gt;Right == NULL)
            T = T-&gt;Left;
        free(P);
    }
    return T;
}

ElementType DeleteMin(SearchTree T)
{
    Position P;
    ElementType X;
    P = FindMin(T);
    X = P-&gt;Element;
    free(P);
    return X;
}

void PrintSearchTree(SearchTree T)
{
    if(T == NULL)
    {
        Error("Element not found");
    }  
    if(T-&gt;Left == NULL &amp;&amp; T-&gt;Right == NULL)
    {
        printf("%d ", T-&gt;Element);
    }else{
        if(T-&gt;Left != NULL)
        {
            PrintSearchTree(T-&gt;Left);
        }
        printf("%d ", T-&gt;Element);
        if(T-&gt;Right != NULL)
        {
            PrintSearchTree(T-&gt;Right);
        }
    }
}

void SearchTreeTest()
{
    SearchTree T;
    T = MakeEmpty(T);
    T = Insert(1,T);
    T = Insert(3,T);
    T = Insert(2,T);
    T = Insert(6,T);
    T = Insert(4,T);
    PrintSearchTree(T);
}

`</pre>

> main.c

<pre class="line-numbers prism-highlight" data-start="1">`#include "searchtree.c"

int main(void)
{
    SearchTreeTest();

    return 0;
}