C++ 使用红黑树的实现及迭代器完成对set和map的封装

一、红黑树的实现以及迭代器

#pragma once
// 要实现完整的迭代器需要对红黑树进行改造，有兴趣可参考侯捷《STL源码剖析》
enum Colour
{RED,BLACK
};template<class T>
struct RBTreeNode
{RBTreeNode<T>* _left;RBTreeNode<T>* _right;RBTreeNode<T>* _parent;T _data;Colour _col;RBTreeNode(const T& data):_left(nullptr), _right(nullptr), _parent(nullptr), _data(data), _col(RED){}
};template<class T, class Ref, class Ptr>
struct RBTreeIterator
{typedef RBTreeNode<T> Node;typedef RBTreeIterator<T, Ref, Ptr> Self;Node* _node;RBTreeIterator(Node* node):_node(node){}// 迭代器的++操作，让迭代器可以移动// 左根右,当右没有访问完,就要继续访问Self& operator++(){if (_node->_right){// 下一个就是右子树的最左节点Node* cur = _node->_right;while (cur->_left){cur = cur->_left;}_node = cur;}else{// 左子树 根 右子树// 右为空，找孩子是父亲左的那个祖先Node* cur = _node;Node* parent = _node->_parent;while (parent && cur == parent->_right){cur = parent;parent = cur->_parent;}_node = parent;}return *this;}self& operator--(){//如果左子树存在if (_node->left){//找左子树的最右节点Node* right = _node->_left;while (right->_right){right = right->_right;}_node = rihgt;}//如果左子树不存在else{//找孩子不是父亲左节点的节点Node* parent = _node->parent;Node* cur = _node;while (parent->_left == cur){cur = cur->_parent;parent = parent->_parent;if (parent == nullptr){break;}}_node = parent;}return *this;}// 下面两个操作，让迭代器可以像指针一样操作T& operator*(){return _node->_data;}T* operator->(){return &_node->_data;}// 下面两个操作，让迭代器能够支持比较bool operator!=(const Self& s)const{return _node != s._node;}bool operator==(const Self& s)const{return _node == s._node;}
};template<class K, class T, class KeyOfT>
class RBTree
{typedef RBTreeNode<T> Node;
public:typedef RBTreeIterator<T, T&, T*> Iterator;typedef RBTreeIterator<T, const T&, const T*> const_Iterator;Iterator Begin(){Node* cur = _root;while (cur && cur->_left){cur = cur->_left;}return Iterator(cur);}Iterator End(){return Iterator(nullptr);}const_Iterator Begin() const{Node* cur = _root;while (cur->_left)cur = cur->_left;return const_Iterator(cur);}const_Iterator End() const{return const_Iterator(nullptr);}~RBTree(){Destroy(_root);_root = nullptr;}pair<Node*, bool> Insert(const T& data){if (_root == nullptr){_root = new Node(data);_root->_col = BLACK;return make_pair(_root,true);}KeyOfT kot;Node* parent = nullptr;Node* cur = _root;while (cur){if (kot(cur->_data) < kot(data)){parent = cur;cur = cur->_right;}else if (kot(cur->_data) > kot(data)){parent = cur;cur = cur->_left;}else{return make_pair(cur, false);}}cur = new Node(data);Node* newnode = cur;// 新增节点。颜色红色给红色cur->_col = RED;if (kot(parent->_data) < kot(data)){parent->_right = cur;}else{parent->_left = cur;}cur->_parent = parent;while (parent && parent->_col == RED){Node* grandfather = parent->_parent;//    g//  p   uif (parent == grandfather->_left){Node* uncle = grandfather->_right;if (uncle && uncle->_col == RED){// u存在且为红 -》变色再继续往上处理parent->_col = uncle->_col = BLACK;grandfather->_col = RED;cur = grandfather;parent = cur->_parent;}else{// u存在且为黑或不存在 -》旋转+变色if (cur == parent->_left){//    g//  p   u//c//单旋RotateR(grandfather);parent->_col = BLACK;grandfather->_col = RED;}else{//    g//  p   u//    c//双旋RotateL(parent);RotateR(grandfather);cur->_col = BLACK;grandfather->_col = RED;}break;}}else{//    g//  u   pNode* uncle = grandfather->_left;// 叔叔存在且为红，-》变色即可if (uncle && uncle->_col == RED){parent->_col = uncle->_col = BLACK;grandfather->_col = RED;// 继续往上处理cur = grandfather;parent = cur->_parent;}else // 叔叔不存在，或者存在且为黑{// 情况二：叔叔不存在或者存在且为黑// 旋转+变色//      g//   u     p//            cif (cur == parent->_right){RotateL(grandfather);parent->_col = BLACK;grandfather->_col = RED;}else{//		g//   u     p//      cRotateR(parent);RotateL(grandfather);cur->_col = BLACK;grandfather->_col = RED;}break;}}}_root->_col = BLACK;return make_pair(newnode, true);}bool empty()const{if (_root == nullptr)return true;return false;}Node* Find(const K& key){Node* cur = _root;while (cur){if (cur->_kv.first < key){cur = cur->_right;}else if (cur->_kv.first > key){cur = cur->_left;}else{return cur;}}return nullptr;}size_t Size() const{return _Size(_root);}private:size_t _Size(Node* root) const{if (root == nullptr)return 0;return _Size(root->_left)+ _Size(root->_right) + 1;}void RotateL(Node* parent){Node* subR = parent->_right;Node* subRL = subR->_left;parent->_right = subRL;if (subRL)subRL->_parent = parent;Node* parentParent = parent->_parent;subR->_left = parent;parent->_parent = subR;if (parentParent == nullptr){_root = subR;subR->_parent = nullptr;}else{if (parent == parentParent->_left){parentParent->_left = subR;}else{parentParent->_right = subR;}subR->_parent = parentParent;}}void  RotateR(Node* parent){Node* subL = parent->_left;Node* subLR = subL->_right;parent->_left = subLR;if (subLR)subLR->_parent = parent;Node* parentParent = parent->_parent;subL->_right = parent;parent->_parent = subL;if (parentParent == nullptr){_root = subL;subL->_parent = nullptr;}else{if (parent == parentParent->_left){parentParent->_left = subL;}else{parentParent->_right = subL;}subL->_parent = parentParent;}}void Destroy(Node* root){if (root == nullptr)return;Destroy(root->_left);Destroy(root->_right);delete root;}private:Node* _root = nullptr;
};

二、set

#pragma once
#include"RBTree_iterator.h"namespace XY 
{template<class K>class set{typedef K ValueType;struct KeyOfValue{const K& operator()(const ValueType& data){return data;}};public:// 这里加typename的原因是告诉编译器这是模板不是类型// 还没实例化typedef typename  RBTree<ValueType, ValueType,KeyOfValue>::const_Iterator iterator;typedef typename  RBTree<ValueType, ValueType,KeyOfValue>::const_Iterator const_iterator;iterator begin() const{return t.Begin();}iterator end() const{return t.End();}bool empty()const{return t.empty();}size_t size()const{return t.Size();}pair<iterator, bool> insert(const ValueType& data){return t.Insert(data);}void clear(){t.Destroy();}iterator find(const K& key){t.Find(key);}private:RBTree<ValueType, ValueType, KeyOfValue> t;};
}

三、map

#pragma once#include"RBTree_iterator.h"namespace XY   
{template<class K, class V>class map{typedef pair<K, V> ValueType;struct KeyOfValue{const K& operator()(const ValueType& data){return data.first;}};public:// 这里加typename的原因是告诉编译器这是模板不是类型// 还没实例化typedef typename RBTree<ValueType, pair<const K, V>, KeyOfValue>::Iterator iterator;typedef typename RBTree<ValueType, pair<const K, V>, KeyOfValue>::const_Iterator const_iterator;iterator begin(){return t.Begin();}iterator end(){return t.End();}const_iterator cbegin() const{return t.Begin();}const_iterator cend() const{return t.End();}bool empty()const{return t.empty();}size_t size()const{return t.Size();}V& operator[](const K& key){pair<iterator, bool> ret = insert(make_pair(key, V()));return ret.first->second;}pair<iterator, bool> insert(const ValueType& data){return t.Insert(data);}void clear(){t.Destroy();}iterator find(const K& key){t.Find(key);}private:RBTree<ValueType, pair<const K, V>, KeyOfValue> t;};
}