[C++] Binary search tree KV model

In the most typical scenario, automatic translation software, input Chinese, output the corresponding English, input English, output the corresponding Chinese.

This function can be realized by searching a binary tree.

K->key V->val

The basic structure is the same as the ordinary search binary tree, except that there is one more member _valand one more parameter V in the template.

If you don’t know the binary search tree, you can read my other blog.

namespace kv
{
	template<class K, class V>
	struct BSTreeNode
	{
		BSTreeNode<K, V>* _left;
		BSTreeNode<K, V>* _right;
		K _key;
		V _value;

		BSTreeNode(const K& key, const V& value)
			:_left(nullptr)
			, _right(nullptr)
			, _key(key)
			, _value(value)
		{}
	};

	template<class K, class V>
	class BSTree
	{
		typedef BSTreeNode<K, V> Node;
	public:
		bool Insert(const K& key, const V& value)
		{
			if (_root == nullptr)
			{
				_root = new Node(key, value);
				return true;
			}

			Node* parent = nullptr;
			Node* cur = _root;
			while (cur)
			{
				if (cur->_key < key)
				{
					parent = cur;
					cur = cur->_right;
				}
				else if (cur->_key > key)
				{
					parent = cur;
					cur = cur->_left;
				}
				else
				{
					return false;
				}
			}

			cur = new Node(key, value);
			if (parent->_key < key)
			{
				parent->_right = cur;
			}
			else
			{
				parent->_left = cur;
			}

			return true;
		}

		Node* Find(const K& key)
		{
			Node* cur = _root;
			while (cur)
			{
				if (cur->_key < key)
				{
					cur = cur->_right;
				}
				else if (cur->_key > key)
				{
					cur = cur->_left;
				}
				else
				{
					return cur;
				}
			}

			return nullptr;
		}

		bool Erase(const K& key)
		{
			//...

			return true;
		}

		void InOrder()
		{
			_InOrder(_root);
			cout << endl;
		}
	private:

		void _InOrder(Node* root)
		{
			if (root == nullptr)
			{
				return;
			}

			_InOrder(root->_left);
			cout << root->_key << ":" << root->_value << endl;
			_InOrder(root->_right);
		}
	private:
		Node* _root = nullptr;
	};

Test the function:

What if you want to implement a count of the number of words?

Then just construct a <string,int>type, string records words, and int records numbers.

	void TestBSTree2()
	{
		string arr[] = { "香蕉", "苹果", "香蕉", "草莓", "香蕉", "苹果", "苹果", "苹果" };

		BSTree<string, int> countTree;
		for (auto& str : arr)
		{
			//BSTreeNode<string, int>* ret = countTree.Find(str);
			auto ret = countTree.Find(str);
			if (ret)
			{
				ret->_value++;
			}
			else
			{
				countTree.Insert(str, 1);
			}
		}

		countTree.InOrder();
	}

Sum code:

#include<iostream>
using namespace std;

namespace kv
{
	template<class K, class V>
	struct BSTreeNode
	{
		BSTreeNode<K, V>* _left;
		BSTreeNode<K, V>* _right;
		K _key;
		V _value;

		BSTreeNode(const K& key, const V& value)
			:_left(nullptr)
			, _right(nullptr)
			, _key(key)
			, _value(value)
		{}
	};

	template<class K, class V>
	class BSTree
	{
		typedef BSTreeNode<K, V> Node;
	public:
		bool Insert(const K& key, const V& value)
		{
			if (_root == nullptr)
			{
				_root = new Node(key, value);
				return true;
			}

			Node* parent = nullptr;
			Node* cur = _root;
			while (cur)
			{
				if (cur->_key < key)
				{
					parent = cur;
					cur = cur->_right;
				}
				else if (cur->_key > key)
				{
					parent = cur;
					cur = cur->_left;
				}
				else
				{
					return false;
				}
			}

			cur = new Node(key, value);
			if (parent->_key < key)
			{
				parent->_right = cur;
			}
			else
			{
				parent->_left = cur;
			}

			return true;
		}

		Node* Find(const K& key)
		{
			Node* cur = _root;
			while (cur)
			{
				if (cur->_key < key)
				{
					cur = cur->_right;
				}
				else if (cur->_key > key)
				{
					cur = cur->_left;
				}
				else
				{
					return cur;
				}
			}

			return nullptr;
		}

		bool Erase(const K& key)
		{
			//...

			return true;
		}

		void InOrder()
		{
			_InOrder(_root);
			cout << endl;
		}
	private:

		void _InOrder(Node* root)
		{
			if (root == nullptr)
			{
				return;
			}

			_InOrder(root->_left);
			cout << root->_key << ":" << root->_value << endl;
			_InOrder(root->_right);
		}
	private:
		Node* _root = nullptr;
	};

	void TestBSTree1()
	{
		BSTree<string, string> dict;
		dict.Insert("sort", "排序");
		dict.Insert("left", "左边");
		dict.Insert("right", "右边");
		dict.Insert("string", "字符串");
		dict.Insert("insert", "插入");
		string str;
		while (cin >> str)
		{
			BSTreeNode<string, string>* ret = dict.Find(str);
			if (ret)
			{
				cout << "对应的中文:" << ret->_value << endl;
			}
			else
			{
				cout << "对应的中文->无此单词" << endl;
			}
		}
	}

	void TestBSTree2()
	{
		string arr[] = { "香蕉", "苹果", "香蕉", "草莓", "香蕉", "苹果", "苹果", "苹果" };

		BSTree<string, int> countTree;
		for (auto& str : arr)
		{
			//BSTreeNode<string, int>* ret = countTree.Find(str);
			auto ret = countTree.Find(str);
			if (ret)
			{
				ret->_value++;
			}
			else
			{
				countTree.Insert(str, 1);
			}
		}

		countTree.InOrder();
	}
}