二叉树的非递归建立

1. 问题描述:

先序非递归建立一颗以二叉链表为存储结构的二叉树。例如建立如下所示的一颗二叉树

                                 A

                             /        

                         B             E

                      /              /      

                   C        D   F        

则输入应为: ABC_ _D_ _EF_ _ _      (其中_代表空格).

/*
 *  名 称: 建立二叉树(非递归)
 *  作 者: Brooke gao
 *  时 间: 2013/8/21
 *  
*/
    
#include<stdio.h>
#include<stdlib.h>
#include<malloc.h>

#define STACKSIZE 50
#define bitree_size(tree)  ((tree)->size)   
#define bitree_root(tree)  ((tree)->root)
#define bitree_left(node)  ((node)->left)
#define bitree_right(node) ((node)->right)

/*
 *  定义二叉树结点以及二叉树的结构
 *
*/
typedef struct BiTreeNode_
{
    char data;
    struct BiTreeNode_ *left;
    struct BiTreeNode_ *right;
}BiTreeNode;

typedef struct BiTree_
{
    int size;
    BiTreeNode *root;
}BiTree;

/*
 *  定义栈的结构
 *
*/
typedef struct Stack_
{
    BiTreeNode * base[STACKSIZE];
    int top;
    int stacksize;
}Stack;

void stack_init(Stack *stack)
{
    stack->top = -1;
    stack->stacksize = 0;
}

void push(Stack *stack, BiTreeNode *node)
{
    if(stack->stacksize == STACKSIZE)
        exit(-1);

    stack->base[++stack->top] = node;
    stack->stacksize++;
}

int stack_empty(Stack *stack)
{
    if((-1 == stack->top) && (0 == stack->stacksize))
        return 1;
    else
        return 0;
}

BiTreeNode* pop(Stack *stack)
{
    if(stack->top < 0)
        exit(-1);
    else
    {
        stack->stacksize--;
        return stack->base[stack->top--];
    }
}

BiTreeNode* get_stack_top(Stack *stack)
{
    if(stack->top < 0)
        exit(-1);
    return stack->base[stack->top];
}

void bitree_init(BiTree *tree)
{
    tree->size = 0;
    tree->root = NULL;
}

//给树tree的某个结点node插入数据域为data的左子树
int bitree_ins_left(BiTree *tree, BiTreeNode *node, const char data)
{
    BiTreeNode *new_node, **position;

    if(NULL == node)
    {
        if(bitree_size(tree) > 0)
            return -1;
        position = &tree->root;
    }
    else
    {
        if(bitree_left(node) != NULL)
            return -1;
        position = &node->left;
    }

    if( NULL == (new_node = (BiTreeNode *)malloc(sizeof(BiTreeNode))) )
        return -1;
    new_node->data = data;
    new_node->left = NULL;
    new_node->right = NULL;
    *position = new_node;
    tree->size++;
        
    return 0;
}

//给树tree的某个结点node插入数据域为data的右子树
int bitree_ins_right(BiTree *tree, BiTreeNode *node, const char data)
{
    BiTreeNode *new_node, **position;

    if(NULL == node)
    {
        if(bitree_size(tree) > 0)
            return -1;

        position = &tree->root;
    }
    else
    {
        if(bitree_right(node) != NULL)
            return -1;

        position = &node->right;
    }

    if( NULL == (new_node = (BiTreeNode *)malloc(sizeof(BiTreeNode))) )
        return -1;

    new_node->data = data;
    new_node->left = NULL;
    new_node->right = NULL;

    *position = new_node;

    tree->size++;
    return 0;
}

// 先序遍历函数
void pre_order(const BiTreeNode *node)
{
    if(node)
    {
        printf("%c",node->data);
        pre_order(node->left);
        pre_order(node->right);
    }
}

// 中序遍历函数
void in_order(const BiTreeNode *node)
{
    if(node)
    {
        in_order(node->left);
        printf("%c",node->data);
        in_order(node->right);
    }
}

// 后序遍历函数
void end_order(const BiTreeNode *node)
{
    if(node)
    {
        end_order(node->left);
        end_order(node->right);
        printf("%c",node->data);
    }
}

int main()
{
    char data;
    Stack stack;
    BiTree tree;
    BiTreeNode *node;
    
    stack_init(&stack);
    bitree_init(&tree);

    printf("请以先序顺序输入结点值: 
");

    data = getchar();
    
    if( 0 == bitree_size(&tree) )
    {
        if( ' ' == data )
            return -1;
        bitree_ins_left(&tree,NULL,data);
        push(&stack,tree.root);
    }
    while(!stack_empty(&stack))
    {
        data = getchar();

        if( ' ' == data )
        {
            node = pop(&stack);
            
            if(NULL == node->left)
            {
                data = getchar();
                if( ' ' != data )
                {
                    bitree_ins_right(&tree,node,data);
                    push(&stack,node->right);
                }
            }
        }
        else
        {
            node = get_stack_top(&stack);
            if( NULL == node->left )
            {
                bitree_ins_left(&tree,node,data);
                push(&stack,node->left);
            }
            else
            {
                node = pop(&stack);
                bitree_ins_right(&tree,node,data);
                push(&stack,node->right);
            }
        }
    }
    printf("-----先序遍历二叉树-----
");
    pre_order(tree.root);
    putchar('
');
    
    printf("-----中序遍历二叉树-----
");
    in_order(tree.root);
    putchar('
');

    printf("-----后序遍历二叉树-----
");
    end_order(tree.root);
    putchar('
');

    return 0;
}