<二叉树的基本操作（有层次遍历）>

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

#define num 100
#define OK 1
#define ERROR 0
#define OVERFLOW -1
#define FALSE 0
#define TRUE 1

typedef int Status;
typedef char DataType;

typedef struct node
{
    DataType data;
    struct node *lchild,*rchild;
}BinTNode,*BinTree;

typedef BinTNode*  ElemType;

#define    QueueSize 100
//循环队列的存储结构
typedef struct
{
    ElemType *base;
    int front,rear;
}SeQueue;


Status CreateBiTree(BinTree &bt)
{//按照先序遍历次序递归建立二叉树。
 //ABC@@DE@G@@F@@
    char ch;
    scanf("%c",&ch);
    if(ch == '@')    bt = NULL;
    else
    {
        bt = (BinTNode*)malloc(sizeof(BinTNode));
        bt->data = ch;        //生成根结点
        CreateBiTree(bt->lchild);    //构造左子树
        CreateBiTree(bt->rchild);    //构造右子树
    }
    return OK;
}

Status Inorder(BinTree bt)
{//二叉树中序遍历非递归算法
    BinTNode *stack[num];    //定义栈数组
    int top = 0;            //初始化栈
    stack[top] = bt;
    do
    {
        while(NULL!=stack[top])
        {//扫描根结点及其所有的左结点并入栈
            top = top+1;
            stack[top] = stack[top-1]->lchild;
        }
        top = top-1;    //退栈
        if(top>=0)        //判断栈是否为空
        {
            printf("%c",stack[top]->data);    //访问结点
            stack[top] = stack[top]->rchild;    //扫描右子树
        }
    }while(top>=0);
    return OK;
}

void PostOrder(BinTree bt)
{//二叉树后序遍历递归算法
    if(bt)
    {
        PostOrder(bt->lchild);
        PostOrder(bt->rchild);
        printf("%c",bt->data);
    }

}

int Size(BinTree bt)
{//统计二叉树中所有结点的个数
    int num1,num2;
    if(bt==NULL)
        return 0;
    else if(bt->lchild==NULL && bt->rchild==NULL)
        return 1;
    else
    {
        num1 = Size(bt->lchild);
        num2 = Size(bt->rchild);
        return (num1+num2+1);
    }
}

int LeafCount(BinTree bt)
{//叶子结点总数为
    int LeafNum;
    if(bt==NULL)
        LeafNum = 0;
    else if((bt->lchild==NULL) && (bt->rchild==NULL))    LeafNum = 1;
    else LeafNum = LeafCount(bt->lchild)+LeafCount(bt->rchild);
    //叶子数为左右子树叶子数目之和
    return LeafNum;
}

int Depth(BinTree bt)
{//统计二叉树深度
    int hl,hr,max;
    if(bt!=NULL)
    {
        hl = Depth(bt->lchild);    //求左子树的深度
        hr = Depth(bt->rchild);    //求右子树的深度
        max = hl>hr?hl:hr;
        return (max+1);    //返回树的深度
    }
    else
        return 0;
}

void Exchange(BinTree bt)
{//交换左右二叉树
    if(bt == NULL)
        return;
    BinTNode *temp;
    temp = bt->lchild;
    bt->lchild = bt->rchild;
    bt->rchild = temp;
    Exchange(bt->lchild);
    Exchange(bt->rchild);
}

//构造一个循环队列
Status InitQueue(SeQueue &Q)
{
    Q.base = (ElemType *)malloc(QueueSize *sizeof(ElemType));
    if(!Q.base)    exit(0);
    Q.front = Q.rear = 0;
    return    OK;
}
//插入新的元素为队尾元素
Status EnQueue(SeQueue &Q,ElemType e)
{
    if((Q.rear+1)%QueueSize==Q.front)
    {
        printf("Queue overflow");
        return 0;
    }
    Q.base[Q.rear] = e;
    Q.rear = (Q.rear+1)%QueueSize;
    return 1;
}

//删除队头元素
Status DeleteQ(SeQueue &Q,ElemType &e)
{
    if(Q.front == Q.rear)
    {
        printf("Queue enpty");
        return ERROR;
    }
    e = Q.base[Q.front];
    Q.front = (Q.front+1)%QueueSize;
    return    OK;
}

//判空循环队列
Status IsEmptyQ(SeQueue Q)
{
    if(Q.front == Q.rear)
        return TRUE;
    else
        return FALSE;
}
//层次遍历二叉树
void LevelOrderTraversal(BinTree bt)
{
    SeQueue Q;
    ElemType e;
//若是空树，则直接返回
    InitQueue(Q);    //创建并初始化队列
    if(bt)  EnQueue(Q,bt);
    while(!IsEmptyQ(Q))
    {
        DeleteQ(Q,e);
        printf("%4c",e->data);
        if(e->lchild)    EnQueue(Q,e->lchild);
        if(e->rchild)   EnQueue(Q,e->rchild);
    }
}

void main()
{
    BinTree bt;
    int xz = 1;
    int yz,sd;
    while(xz)
    {
        printf("二叉树的建立及其基本操作
");
        printf("===========================
");
        printf("1,建立二叉树的存储结构
");
        printf("2,二叉树的基本操作
");
        printf("3,交换二叉树的左右
");
        printf("4,二叉树的层次遍历
");
        printf("0退出系统
");
        printf("==========================
");
        printf("请选择：(0~4)
");
        scanf("%d",&xz);
        getchar();
        switch(xz)
        {//输入：ABC@@DE@G@@F@@@输出：CBEGDFA
        case 1:
            printf("输入二叉树的先序序列结点值：
");
            CreateBiTree(bt);
            printf("二叉树的链式存储结构建立完成
");
            printf("
");
            break;
        case 2:
            printf("该二叉树的后序遍历序列是：");
            PostOrder(bt);
            printf("
");    //输出CGEFDBA
            printf("该二叉树的中序遍历序列是：");
            Inorder(bt);
            printf("
");    //输出CBEGDFA
            printf("该二叉树的结点的个树是：%d
",Size(bt));
            yz = LeafCount(bt);
            printf("叶子结点个数是：%d
",yz);
            sd = Depth(bt);
            printf("该二叉树的深度是：%d
",sd);
            printf("
");
            break;
        case 3:
            Exchange(bt);
            printf("该二叉树已交换左右子树！
");
            printf("
");
            break;
        case 4:
            printf("该二叉树的层序遍历序列是：");
            LevelOrderTraversal(bt);
            printf("
");    //输出ABCDEFG
            break;
        case 0:
            break;
        default:printf("请输入正确的选项：（0~4）：
");

        }
    }
}