建立一個如下圖所示的二叉樹

程式如下：

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

//定義二叉樹
typedef struct _tree_node
{
    char date;
    struct tree_node *lchild;//左節點
    struct tree_node *rchild;//右節點
}tree_node;

//建立二叉樹
tree_node *create_tree_node(tree_node *new_node)
{
    char date = '0';
    scanf("%c", &date);

    if(date == '0')
    {
        new_node = NULL;
        return new_node;
    }
    else
    {
        new_node = (tree_node *)malloc(sizeof(tree_node));
        memset(new_node, 0, sizeof(new_node));

        new_node->date = date;
        new_node->lchild = create_tree_node(new_node->lchild);
        new_node->rchild = create_tree_node(new_node->rchild);
        return new_node;
    }
}

//先序遍歷：跟左右
void pre_traver(tree_node *node)
{
    if(!node)
    {
        return;
    }
    else
    {
        printf("%c\n", node->date);//跟
        pre_traver(node->lchild);//左
        pre_traver(node->rchild);//右
    }
}

//中序遍歷：左跟右
void in_order_traver(tree_node *node)
{
    if(!node)
        return;
    else
    {

        in_order_traver(node->lchild);//左
        printf("%c\n", node->date);//跟
        in_order_traver(node->rchild);//右
    }
}
//後序遍歷：左右跟
void post_order_traver(tree_node *node)
{
    if(!node)
        return;
    else
    {
        post_order_traver(node->lchild);//左
        post_order_traver(node->rchild);//右
        printf("%c\n", node->date);//跟
    }
}
int main()
{
    tree_node *root;
    root = create_tree_node(root);

    printf("pre_traver\n");
    pre_traver(root);

    printf("in_order_traver\n");
    in_order_traver(root);

    printf("post_order_traver\n");
    post_order_traver(root);

}
 

程式執行時按照如下方式輸入：

ea0cb00d00f0hg000

程式執行結果如下：