1. 实现森林先根（已提供）、后根遍历递归算法；
2. 计算森林的叶子节点个数（递归算法）；
3. 计算森林的高度（递归算法）；

代码示例👇

//author:Mitchell_Donovan
//date:4.20
#include<iostream>
using namespace std;

template<class T>
class TreeNode {
    //添加友元类声明，便于森林类Tree对其进行一系列访问与修改
	template<class T>
	friend class Tree;
private:
	T data;
	TreeNode<T>* child;
	TreeNode<T>* brother;
public:
	//无参数的构造函数
	TreeNode() :data(T()), child(NULL), brother(NULL) {}
	//有参数的构造函数
	TreeNode(T value) :data(value), child(NULL), brother(NULL) {}
	//析构函数
	virtual~TreeNode() {
		child = NULL;
		brother = NULL;
	}
	//判断当前结点是否为叶结点
	bool isLeaf() {
		if (child == NULL) {
			return true;
		}
		else {
			return false;
		}
	}
	//返回结点的值
	T getValue() {
		return data;
	}
	//返回左子结点
	TreeNode<T>* getChild() {
		return child;
	}
	//返回右兄弟结点
	TreeNode<T>* getBrother() {
		return brother;
	}
	//设置当前结点的值
	void setValue(const T& value) {
		data = value;
	}
	//设置左子结点
	void setChild(TreeNode<T>* pointer) {
		child = pointer;
	}
	//设置右兄弟结点
	void setBrother(TreeNode<T>* pointer) {
		brother = pointer;
	}
};

template<class T>
class Tree {
private:
	TreeNode<T>* root;
public:
	//构造函数
	Tree() {
		root = NULL;
		cout << "Now start to construct the tree! " << endl;
		cout << "Please enter a value or '#' to stop:";
		createTree(root);
	}
	//析构函数
	virtual~Tree() {
		root = NULL;
	}
	//先序构造森林
	void createTree(TreeNode<T>*& node) {
		T value;
		cin >> value;
		if (value == '#') {
			node = NULL;
		}
		else {
			node = new TreeNode<T>(value);
			createTree(node->child);
			createTree(node->brother);
		}
	}
	//取根结点
	TreeNode<T>* getRoot() {
		return root;
	}
	//先根深度优先周游树
	void rootFirst(TreeNode<T>* node) {
		while (node != NULL) {
			cout << node->data << " ";
			rootFirst(node->child);
			node = node->brother;
		}
	}
	//后根深度优先周游树
	void rootLast(TreeNode<T>* node) {
		while (node != NULL) {
			rootLast(node->child);
			cout << node->data << " ";
			node = node->brother;
		}
	}
	//计算叶结点个数
	int countLeaf(TreeNode<T>* node) {
		int count = 0;
		while (node != NULL) {
			if (node->isLeaf()) {
				count++;
			}
			count += countLeaf(node->child);
			node = node->brother;
		}
		return count;
	}
	//计算深度
	int countDepth(TreeNode<T>* node) {
		if (node == NULL) {
			return 0;
		}
		int depth = 0;
		int childdepth = countDepth(node->child);
		int brotherdepth = countDepth(node->brother);
		depth = childdepth + 1 > brotherdepth ? childdepth + 1 : brotherdepth;
		return depth;
	}
};

int main() {
	//AB#CE#F##D###
	Tree<char> test;
	cout << "\n先根深度优先周游结果是:";
	test.rootFirst(test.getRoot());
	cout << "\n后根深度优先周游是:";
	test.rootLast(test.getRoot());
	cout << "\n叶结点个数是:" << test.countLeaf(test.getRoot());
	cout << "\n深度是:" << test.countDepth(test.getRoot());
}

输出样例👇