C之：微代码——二叉树

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

typedef struct  8 {
    long item;
    int count;
    Node* pLeft;
    Node* pRight;
} Node;

Node* creat_node(long);
Node* add_node(long, Node*);
void list_nodes(Node*);
void free_nodes(Node*);

int main(void)
{
    long newvalue = 0;
    Node* pRoot = NULL;
    char answer = 'n';
    do
    {
        printf("Enter the node value: ");
        scanf("%ld", &newvalue);
        getchar();
        if(pRoot == NULL)
        {
            pRoot = creat_node(newvalue);
        }
        else
        {
            add_node(newvalue, pRoot);
        }
        printf("Do you want to enter another (y/n)? ");
        scanf("%c", &answer);
    } while(tolower(answer) == 'y');

    printf("The values in ascending sequence are: \n");
    list_nodes(pRoot);
    free_nodes(pRoot);

    return 0;
}

Node* creat_node(long value)
{
    Node* pNode = (Node*)malloc(sizeof(Node));
    pNode->item = value;
    pNode->count = 1;
    pNode->pLeft = pNode->pRight = NULL;
    return pNode;
}

Node* add_node(long value, Node* pNode)
{
    if(pNode == NULL)
    {
        return creat_node(value);
    }

    if(value == pNode->item)
    {
        ++pNode->count;
        return pNode;
    }

    else if(value < pNode->item)
    {
        if(pNode->pLeft == NULL)
        {
            pNode->pLeft = creat_node(value);
            return pNode->pLeft;
        }
        else
        {
            return add_node(value, pNode->pLeft);
        }
    }
    else
    {
        if(pNode->pRight == NULL)
        {
            pNode->pRight = creat_node(value);
            return pNode->pRight;
        }
        else
        {
            return add_node(value, pNode->pRight);
        }
    }
}

void list_nodes(Node* pNode)
{
    if(pNode->pLeft != NULL)
    {
        list_nodes(pNode->pLeft);    
    }
    
    printf("%10d x %10ld\n", pNode->count, pNode->item);

    if(pNode->pRight != NULL)
    {
        list_nodes(pNode->pRight);
    }
}

void free_nodes(Node* pNode)
{
    if(pNode == NULL)
    {
        return;
    }

    if(pNode->pLeft != NULL)
    {
        free_nodes(pNode->pLeft);
    }

    if(pNode->pRight != NULL)
    {
        free_nodes(pNode->pRight);
    }

    free(pNode);
}