二叉树面试题（部分）

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#pragma once#include<iostream>#include<stdlib.h>#include<stack>#include<queue>using namespace std;template<class T>struct BinaryTreeNode{    T _data;    BinaryTreeNode<T>* _left;    BinaryTreeNode<T>* _right;    BinaryTreeNode(const T& x)        :_data(x)        , _left(NULL)        , _right(NULL)    {}};template<class T>class BinaryTree{    typedef BinaryTreeNode<T> Node;public:    BinaryTree()        :_root(NULL)    {}    BinaryTree(T *p, size_t n, const T& invalid)    {        size_t index = 0;        _root = _Create(p, n, invalid, index);    }    //前中后序递归遍历    void Prevorder()    {        _PrevOrder(_root);        cout << endl;    }    void Inorder()    {        _Inorder(_root);        cout << endl;    }    void Postorder()    {        _Postorder(_root);        cout << endl;    }    //前中后序非递归遍历    void PrevOrder()    {        _PrevOrder(_root);        cout << endl;    }    void InOrder()    {        _InOrder(_root);        cout << endl;    }    void PostOrder()    {        _PostOrder(_root);        cout << endl;    }    //销毁一棵树    void Destory()    {        _Destory(_root);    }    //二叉树所有节点    size_t BinaryTree_size()    {        return _BinaryTree_size(_root);    }    //二叉树叶子节点    size_t Leafsize()    {        return _Leafsize(_root);    }    //第K层节点    size_t GetKLevelSize(size_t k)    {        return _GetKLevelSize(_root, k);    }    //判断一个节点是否在树中    bool IsIntree(int k)    {        return _IsIntree(_root,k);    }    //层序遍历，利用queue    void LevelOrder()    {        _LevelOrder(_root);        cout << endl;    }    //是否完全二叉树    bool IsCompleteTree()    {        return _IsCompleteTree(_root);    }protected:    //递归前中后序遍历    void _Prevorder(Node* root)    {        if (root == NULL)            return;        else        {            cout << root->_data << "";            _Prevorder(root->_left);            _Prevorder(root->_right);            return;        }    }    void _Inorder(Node* root)    {        if (root == NULL)        {            return;        }        else        {            _Inorder(root->_left);            cout << root->_data << "";            _Inorder(root->_right);            return;        }    }    void _Postorder(Node* root)    {        if (root == NULL)            return;        else        {            _Postorder(root->_left);            _Postorder(root->_right);            cout << root->_data << "";            return;        }    }    //非递归遍历    void _PrevOrder(Node* root)    {        if (root == NULL)        {            return;        }        else        {            stack<Node*> s;            Node* cur = root;            while (cur || !s.empty())            {                while (cur)                {                    cout << cur->_data << "";                    s.push(cur);                    cur = cur->_left;                }                Node* top = s.top();                s.pop();                cur = top->_right;            }            return;        }    }    void _InOrder(Node* root)    {        if (root == NULL)        {            return;        }        else        {            stack<Node*> s;            Node* cur = root;            while (cur || !s.empty())            {                while (cur)                {                    s.push(cur);                    cur = cur->_left;                }                Node* top = s.top();                cout << top->_data << "";                s.pop();                cur = top->_right;            }        }    }    void _PostOrder(Node* root)    {        if (root == NULL)        {            return;        }        else        {            Node* prev = NULL;            Node* cur = root;            stack<Node*> s;            while (cur || !s.empty())            {                while (cur)                {                    s.push(cur);                    cur = cur->_left;                }                Node* top = s.top();                if (NULL == top->_right || top->_right == prev)                {                    cout << top->_data << "";                    prev = top;                    s.pop();                }                else                {                    cur = top->_right;                }            }        }    }    //销毁    void _Destory(Node* root)    {        if (root == NULL)        {            return;        }        else        {            _Destroy(root->_left);            _Destroy(root->_right);            delete root;        }    }    //二叉树所有节点个数    size_t _BinaryTree_size(Node* root)    {        if (root == NULL)        {            return 0;        }        else        {            return _BinaryTree_size(root->_left) + _BinaryTree_size(root->_right) + 1;        }    }    //叶子节点个数    size_t _Leafsize(Node *root)    {        if (root == NULL)        {            return 0;        }        if (root->_left == NULL&&root->_right == NULL)        {            return 1;        }        return _Leafsize(root->_left) + _Leafsize(root->_right);    }    //第k层节点数    size_t _GetKLevelSize(Node* root, size_t n)    {        if (root == NULL || n == 0)        {            return 0;        }        if (n == 1)        {            return 1;        }        return _GetKLevelSize(root->_left,n-1) + _GetKLevelSize(root->_right,n-1);    }    //判断是否在树中    bool _IsIntree(Node* root, int n)    {        if (root == NULL)        {            return false;        }        if (root->_data == n)        {            return true;        }        return _IsIntree(root->_left, n) || _IsIntree(root->_right, n);    }    //层序遍历    void _LevelOrder(Node* root)    {        if (root == NULL)        {            return;         }        else        {            queue<Node*> q;            Node* cur = root;            q.push(cur);            while (!q.empty())            {                Node* front = q.front();                q.pop();                cout << front->_data << "";                if (front->_left)                    q.push(front->_left);                if (front->_right)                    q.push(front->_right);            }        }    }    //是否完全二叉树    bool _IsCompleteTree(Node* root)    {        queue<Node*> q;        if (root)        {            q.push(root);            bool tag = true;            while (!q.empty())            {                Node* front = q.front();                if (front->_left)                {                    if (tag == false)                    {                        return false;                    }                    else                    {                        q.push(front->_left);                    }                }                else                {                    tag = false;                }                if (front->_right)                {                    if (tag == false)                    {                        return false;                    }                    else                    {                        q.push(front->_right);                    }                }                else                {                    tag = false;                }            }            return true;        }        return true;    }private:    Node* _root;    Node* _Create(T* p, size_t n, const T& invalid, size_t& index)    {        Node* root = NULL;        if (index < n&&p[index] != invalid)        {            root = new Node(p[index]);            root->_left = _Create(p, n, invalid, ++index);            root->_right = _Create(p, n, invalid, ++index);        }        return root;    }};//测试代码#define _CRT_SECURE_NO_WARNINGS 1#include"BinaryTreee.h"void TestTree1(){    int array[] = { 1, 2, 4, '#', '#', 5, '#', '#', 3, 6, '#', '#', 7,'#','#' };    BinaryTree<int> t1(array, sizeof(array) / sizeof(array[0]), '#');    t1.Prevorder();    t1.Inorder();    t1.Postorder();    t1.PrevOrder();    t1.InOrder();    t1.PostOrder();    /*t1.Destory();*/    t1.LevelOrder();    bool size = t1.IsCompleteTree();    //size_t size = t1.GetKLevelSize(2);    cout << size << endl;}int main(){    TestTree1();    system("pause");    return 0;}
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