二叉树的非递归遍历

sin — Tue, 16 Mar 2010 01:57:00 GMT

这里的二叉树不是一般的二叉树，而是棵二叉查找树。

#include <stdio.h>
#include <stdlib.h>

#define MAX_SIZE 128

struct node
{
    int        data;
    struct node*    lchild;
    struct node*    rchild;
};

struct bin_search_tree
{
    struct node*    root;
};

void    init_search_tree(struct bin_search_tree *tree);
void    clear_search_tree(struct bin_search_tree *tree);
void    insert_node(struct bin_search_tree *tree, int element);

void    pre_order(struct node *p);
void    in_order(struct node *p);
void    post_order(struct node *p);

void    visit(struct node *p);

int main()
{
    struct bin_search_tree tree;
    int i,arr[] = {40, 30, 50, 11, 27, 98, 74, 79, 9, 150, 37};

    init_search_tree(&tree);
    for (i=0; i<sizeof(arr)/sizeof(int); i++)
    {
        insert_node(&tree, arr[i]);
    }

    //前序遍历
    pre_order(tree.root);
    printf("\n");

    //中序遍历
    in_order(tree.root);
    printf("\n");

    //后续遍历
    post_order(tree.root);
    printf("\n");

    clear_search_tree(&tree);
    getchar();
    return 0;
}

/*
* 二叉树的初始化
*/
void init_search_tree(struct bin_search_tree *tree)
{
    tree->root = NULL;
}

/*
* 清除二叉树，用二叉树层次遍历
*/
void clear_search_tree(struct bin_search_tree *tree)
{
    int i,j;
    struct node *p,*queue[MAX_SIZE];

    i = j = 0;
    queue[0] = tree->root;

    while (i<=j)
    {
        for ( ; i<=j; i++ )
        {
            p = queue[i];

            if (p->lchild)
                queue[++j] = p->lchild;
            if (p->rchild)
                queue[++j] = p->rchild;
        }
    }

    for (i=0; i<=j; i++)
    {
        free(queue[i]);
    }

    tree->root = NULL;
}

/*
* 二叉树中插入节点element
*/
void insert_node(struct bin_search_tree *tree, int element)
{
    struct node    *p = tree->root;
    struct node *child, *newnode;

    newnode = (struct node*)malloc(sizeof(struct node));
    newnode->data = element;
    newnode->lchild = NULL;
    newnode->rchild = NULL;

    if (tree->root == NULL)
    {
        tree->root = newnode;
        return;
    }

    while (p)
    {
        if ( element < p->data )
        {
            child = p->lchild;
            if (NULL == child)
            {
                p->lchild = newnode;
                return;
            }
        }
        else
        {
            child = p->rchild;
            if (NULL == child)
            {
                p->rchild = newnode;
                return;
            }
        }

        p = child;
    }
}

/*
* 前序遍历，非递归
*/
void pre_order(struct node *p)
{
    int top = -1;
    struct node *stack[MAX_SIZE];

    if (p == NULL)
        return;

    stack[++top] = p;
    while (top>-1)
    {
        visit(p=stack[top--]);

        if (p->rchild)
            stack[++top] = p->rchild;
        if (p->lchild)
            stack[++top] = p->lchild;
    }
}

/*
* 中序遍历，非递归
*/
void in_order(struct node *p)
{
    int top = -1;
    struct node *stack[MAX_SIZE];

    while (top>-1 || p!=NULL)
    {
        while (p)
        {
            stack[++top] = p;
            p = p->lchild;
        }
        visit(p=stack[top--]);
        p = p->rchild;
    }
}

/*
* 后序遍历，非递归
*/
void post_order(struct node *p)
{
    int top = -1;
    int flag[MAX_SIZE];
    struct node *stack[MAX_SIZE];

    while (top>-1 || p!= NULL)
    {
        while (p)        //将p的所有左节点压入栈
        {
            stack[++top] = p;
            flag[top] = 0;
            p = p->lchild;
        }

        p = stack[top];    //弹出栈顶
        if (flag[top--]==0 && p->rchild)
        {
            stack[++top] = p;
            flag[top] = 1;
            p = p->rchild;
        }
        else
        {
            visit(p);
            p = NULL;    //将p置为NULL，防止进入while(p)循环
        }
    }
}

/*
* 访问一个节点
*/
void visit(struct node *p)
{
    printf("%d  ", p->data);
}

sin 2010-03-16 09:57 发表评论

常用排序算法实现(C语言)

sin — Fri, 12 Mar 2010 14:02:00 GMT

摘要: 排序算法原理都不难，实现起来却没那么简单，特别是一些边界问题的处理。前些天把这些常有的排序算法实现了一遍，代码写的也不太好，很多i,j,k之类的变量，也很多循环嵌套，不过初步测试是正确的。 Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> ... 阅读全文

sin 2010-03-12 22:02 发表评论

C++博客-Ah.........FreshMeat.-随笔分类-数据结构算法

二叉树的非递归遍历

常用排序算法实现(C语言)