二叉树基本操作--创建，三种遍历，叶子节点

#include <iostream>
using namespace std;

//节点的定义
typedef struct BTNode
{
    int data;
    BTNode* rChild;
    BTNode* lChild;
}BiTNode, *BiTree;


//二叉树的创建，先序创建二叉树
int CreateBiTree(BiTNode** T)
{
    int ch;
    cin >> ch;
    if (ch==-1)
    {
        *T = nullptr;
        return 0;
    }
    else
    {
        //*T = new BiTNode();
        *T = (BiTNode*)malloc(sizeof(BiTNode));
        if (T==nullptr)
        {
            cout << "failed!\n";
            return 0;
        }
        else
        {
            (*T)->data = ch;
            cout << "输入左子节点：";
            //cin >> ch;
            CreateBiTree(&(*T)->lChild);
            cout << endl;
            cout << "输入右子节点：";
            //cin >> ch;
            CreateBiTree(&(*T)->rChild);
        }
    }
    return 1;
}


//先序遍历二叉树
void PreOrderBiTree(BiTNode* T)
{
    if (T == nullptr)
    {
        return;
    }
    else
    {
        cout << T->data<<" ";
        PreOrderBiTree(T->lChild);
        PreOrderBiTree(T->rChild);
    }
}

//中序遍历二叉树
void InOrderBiTree(BiTNode* T)
{
    if (T == nullptr)
    {
        return;
    }
    else
    {
        InOrderBiTree(T->lChild);
        cout << T->data << " ";
        InOrderBiTree(T->rChild);
    }
}

//后续遍历二叉树
void PostOrderBiTree(BiTNode* T)
{
    if (T == nullptr)
    {
        return;
    }
    else
    {
        PostOrderBiTree(T->lChild);
        PostOrderBiTree(T->rChild);
        cout << T->data << " ";
    }
}

//树高....

//叶子节点个数
int LeafCount(BiTNode* T)
{
    static int count = 0;
    if (T!=nullptr)
    {
        if (T->lChild==nullptr&&T->rChild==nullptr)
        {
            count++;
        }
        LeafCount(T->lChild);
        LeafCount(T->rChild);
    }
    return count;
}

//客户端测试
int main()
{
    BiTNode* T;
    int leafCount = 0;
    cout << "请输入第一个节点的值，-1表示没有节点：\n";
    CreateBiTree(&T);

    cout << "先序遍历二叉树：";
    PreOrderBiTree(T);
    cout << endl;

    cout << "中序遍历二叉树：";
    InOrderBiTree(T);
    cout << endl;

    cout << "后序遍历二叉树: ";
    PostOrderBiTree(T);
    cout << endl;

    leafCount = LeafCount(T);
    cout << "叶子节点的个数：" <<leafCount<< endl;


    return 0;
}