二叉树子系统

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

typedef char datatype;
typedef struct BitNode
{
    datatype data;
    struct BitNode *lchild, *rchild;
}BT;

char sh = '0';    //判断是否为根结点

BT *create_tree()
{
    BT *bt;
    char x;

    if (sh == '0')
    {
        printf("\n请按先序序列输入二叉树结点。'0'表示后继结点为空。\n请输入根结点: ");
        sh = '1';
    }
    scanf("%c", &x);
    getchar();
    if (x == '0')
        bt = NULL;
    else
    {
        bt = (BT *)malloc(sizeof(BT));
        bt->data = x;
        printf("请输入%c结点的左结点: ", x);
        bt->lchild = create_tree();
        printf("请输入%c结点的右结点: ", x);
        bt->rchild = create_tree();
    }
    return bt;
}

void preorder(BT *bt)
{
    if (bt == NULL)
        return;
    printf("%c ", bt->data);
    preorder(bt->lchild);
    preorder(bt->rchild);
}

void inorder(BT *bt)
{
    if (bt == NULL)
        return;
    inorder(bt->lchild);
    printf("%c ", bt->data);
    inorder(bt->rchild);
}

void postorder(BT *bt)
{
    if (bt == NULL)
        return;
    postorder(bt->lchild);
    postorder(bt->rchild);
    printf("%c ", bt->data);
}

void levelorder(BT *bt)
{
    if (bt == NULL)
        return;
    int i = 0,j = 1;
    BT *str[100], *p;
    str[0] = bt;
    while (i != j)
    {
        p = str[i];
        printf("%c ", p->data);
        if (p->lchild != NULL)
        {
            str[j] = p->lchild;
            j++;
        }
        if (p->rchild != NULL)
        {
            str[j] = p->rchild;
            j++;
        }
        i++;
    }
}

int num = 0;
void leafnum(BT *bt)
{
    if (bt != NULL)
    {
        if (bt->lchild == NULL && bt->rchild == NULL)
            num++;
        leafnum(bt->lchild);
        leafnum(bt->rchild);
    }
}

void nodenumber(BT *bt)
{
    if (bt != NULL)
    {
        num++;
        nodenumber(bt->lchild);
        nodenumber(bt->rchild);
    }
}

int treedepth(BT *bt)
{
    int ldep, rdep;
    if (bt == NULL)
        return 0;
    else
    {
        ldep = treedepth(bt->lchild);
        rdep = treedepth(bt->rchild);
        if (ldep > rdep)
            return ldep + 1;
        else
            return rdep + 1;
    }
}

void caidan()
{
    printf("\n\t\t 二叉树子系统 \n");
    printf("\t\t***********************************************\n");
    printf("\t\t* 1----建二叉树 *\n");
    printf("\t\t* 2----先序遍历 *\n");
    printf("\t\t* 3----中序遍历 *\n");
    printf("\t\t* 4----后序遍历 *\n");
    printf("\t\t* 5----层次遍历 *\n");
    printf("\t\t* 6----求叶子数 *\n");
    printf("\t\t* 7----求结点数 *\n");
    printf("\t\t* 8----求树深度 *\n");
    printf("\t\t* 0----返回 *\n");
    printf("\t\t***********************************************\n");
}

int main()
{
    while (1)
    {
        int ch;
        BT *bt;
        caidan();
        printf("\n请选择菜单号<0-9>: ");
        scanf("%d", &ch);
        getchar();
        switch(ch)
        {
            case 1:
                bt = create_tree();
                printf("二叉树建立成功。\n");
                break;
            case 2:
                printf("二叉树先序遍历为: ");
                preorder(bt);
                break;
            case 3:
                printf("二叉树中序遍历为: ");
                inorder(bt);
                break;
            case 4:
                printf("二叉树后序遍历为: ");
                postorder(bt);
                break;
            case 5:
                printf("二叉树层次遍历为: ");
                levelorder(bt);
                break;
            case 6:
                num = 0;
                printf("二叉树叶子数为: ");
                leafnum(bt);
                printf("%d\n", num);
                break;
            case 7:
                num = 0;
                printf("二叉树结点数为: ");
                nodenumber(bt);
                printf("%d\n", num);
                break;
            case 8:
                printf("树的深度为：");
                int dep = treedepth(bt);
                printf("%d\n", dep);
                break;
            case 0:
                printf("程序结束！\n");
                return;
        }
    }

    return 0;
}