C++ —— 用一棵红黑树同时封装出map和set
- 总览
- RBTree
- MyMap
- MySet
- 红黑树源代码
- 红黑树模板参数的控制
- 模板参数中仿函数的增加
- 迭代器模拟
- 1. 迭代器的定义和结构
- 2. 迭代器的操作符重载
- set模拟
- map模拟
- 代码
- 红黑树的代码
- set的代码
- map的代码
总览
RBTree
enum Colour
{RED,BLACK
};// RBTree节点
template<class T>
struct RBTreeNode
{RBTreeNode<T>* _left;RBTreeNode<T>* _right;RBTreeNode<T>* _parent;Colour _col;T _data;RBTreeNode(const T& data): _left(nullptr), _right(nullptr), _parent(nullptr), _col(RED), _data(data){}
};// RBTree迭代器
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) {}Ref operator*();Ptr operator->();bool operator!=(const Self& s);Self& operator++();
};// RBTree实现
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*> ConstIterator;RBTree() = default;RBTree(const RBTree<K, T, KeyOfT>& t);~RBTree();RBTree<K, T, KeyOfT>& operator=(RBTree<K, T, KeyOfT> t);Iterator Begin();Iterator End();ConstIterator Begin() const;ConstIterator End() const;Iterator Find(const K& key);std::pair<Iterator, bool> Insert(const T& data);void RotateR(Node* parent);void RotateL(Node* parent);void InOrder();bool IsBalance() const;private:Node* Copy(Node* root);void Destroy(Node* root);bool Check(Node* root, int blackNum, const int refNum) const;void _InOrder(Node* root) const;Node* _root = nullptr;
};
MyMap
namespace qq
{template<class K, class V>class map{struct MapKeyOfT{const K& operator()(const std::pair<K, V>& kv);};public:typedef typename RBTree<K, std::pair<const K, V>, MapKeyOfT>::Iterator iterator;typedef typename RBTree<K, const std::pair<K, V>, MapKeyOfT>::ConstIterator const_iterator;const_iterator begin() const;const_iterator end() const;iterator begin();iterator end();iterator find(const K& key);std::pair<iterator, bool> insert(const std::pair<K, V>& kv);V& operator[](const K& key);private:RBTree<K, std::pair<const K, V>, MapKeyOfT> _t;};
}
MySet
namespace qq
{template<class K>class set{struct SetKeyOfT{const K& operator()(const K& key);};public:typedef typename RBTree<K, const K, SetKeyOfT>::Iterator iterator;typedef typename RBTree<K, const K, SetKeyOfT>::ConstIterator const_iterator;const_iterator begin() const;const_iterator end() const;iterator begin();iterator end();iterator find(const K& key);std::pair<iterator, bool> insert(const K& key);private:RBTree<K, const K, SetKeyOfT> _t;};
}
红黑树源代码
enum Colour
{RED,BLACK
};template<class K, class V>
struct RBTreeNode
{RBTreeNode<K, V>* _left;RBTreeNode<K, V>* _right;RBTreeNode<K, V>* _parent;pair<K, V> _kv;Colour _col;RBTreeNode(const pair<K, V>& kv):_left(nullptr), _right(nullptr), _parent(nullptr), _kv(kv), _col(RED){}
};template<class K, class V>
class RBTree
{typedef RBTreeNode<K, V> Node;
public:bool Insert(const pair<K, V>& kv){if (_root == nullptr){_root = new Node(kv);_root->_col = BLACK;return true;}Node* parent = nullptr;Node* cur = _root;while (cur){if (cur->_kv.first < kv.first){parent = cur;cur = cur->_right;}else if (cur->_kv.first > kv.first){parent = cur;cur = cur->_left;}else{return false;}}cur = new Node(kv);cur->_col = RED; // 新增节点给红色if (parent->_kv.first < kv.first){parent->_right = cur;}else{parent->_left = cur;}cur->_parent = parent;// parent的颜色是黑色也结束while (parent && parent->_col == RED){// 关键看叔叔Node* grandfather = parent->_parent;if (parent == grandfather->_left){Node* uncle = grandfather->_right;// 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{if (cur == parent->_left){// g // p u// c RotateR(grandfather);parent->_col = BLACK;grandfather->_col = RED;}else{// g // p u// c RotateL(parent);RotateR(grandfather);cur->_col = BLACK;grandfather->_col = RED;}break;}}else{Node* 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 true;}void RotateR(Node* parent){Node* subL = parent->_left;Node* subLR = subL->_right;parent->_left = subLR;if (subLR)subLR->_parent = parent;subL->_right = parent;Node* ppNode = parent->_parent;parent->_parent = subL;if (parent == _root){_root = subL;_root->_parent = nullptr;}else{if (ppNode->_left == parent){ppNode->_left = subL;}else{ppNode->_right = subL;}subL->_parent = ppNode;}}void RotateL(Node* parent){Node* subR = parent->_right;Node* subRL = subR->_left;parent->_right = subRL;if (subRL)subRL->_parent = parent;subR->_left = parent;Node* ppNode = parent->_parent;parent->_parent = subR;if (parent == _root){_root = subR;_root->_parent = nullptr;}else{if (ppNode->_right == parent){ppNode->_right = subR;}else{ppNode->_left = subR;}subR->_parent = ppNode;}}void InOrder(){_InOrder(_root);cout << endl;}bool IsBalance(){if (_root->_col == RED){return false;}int refNum = 0;Node* cur = _root;while (cur){if (cur->_col == BLACK){++refNum;}cur = cur->_left;}return Check(_root, 0, refNum);}private:bool Check(Node* root, int blackNum, const int refNum){if (root == nullptr){//cout << blackNum << endl;if (refNum != blackNum){cout << "存在黑色节点的数量不相等的路径" << endl;return false;}return true;}if (root->_col == RED && root->_parent->_col == RED){cout << root->_kv.first << "存在连续的红色节点" << endl;return false;}if (root->_col == BLACK){blackNum++;}return Check(root->_left, blackNum, refNum)&& Check(root->_right, blackNum, refNum);}void _InOrder(Node* root){if (root == nullptr){return;}_InOrder(root->_left);cout << root->_kv.first << ":" << root->_kv.second << endl;_InOrder(root->_right);}private:Node* _root = nullptr;//size_t _size = 0;
};
红黑树模板参数的控制
因为set
是K模型的容器,而map
是KV模型的容器,我们上面实现的红黑树是KV模型的红黑树,那怎么去使用KV的红黑树来同时实现set
和map
呢?
这里我们就需要更改红黑树的模板参数了,讲红黑树的第二个模板参数更改为T
。
template<class K, class T>
class RBTree
当我们模拟实现set
时,只需控制T
传入Key,如果模拟实现map
时,则需要给T传入K 和 V。
如下图:
为什么要保留第一个模板参数是K?
我们可以通过第二个模板参数
T
来决定传入的是K还是KV,那为什么还要保留第一个K?
例如,在
Find
函数中,你需要传入一个键值来查找相应的元素。由于键的类型可能与存储的值类型不同,单独保存键的类型允许你灵活地处理不同的键类型。
示例:如果你的树存储的是std::pair<int, std::string>
,但你想用 int 作为键来查找元素,那么你需要K
作为键的类型。K
允许 RBTree 区分存储的实际数据类型和用作索引的键类型。
模板参数中仿函数的增加
因为我们现在不知道红黑树代码模板的第二个参数传入的是K还是pair,所以在后续的操作(比如比大小等)时会出现问题,所以这里我们使用一个仿函数来达到取值的目的。
如果是set
,那么这里的仿函数则直接返回第二个模板参数的k即可。
如果是map
,那么这里的仿函数则根据map
的取值规则,返回pair<k,v>
的k
即可。
仿函数是重载运算符(),通过对象调用函数来是使用。具体的仿函数可以参考这篇博客priority_queue的模拟实现
class set
{struct SetKeyOfT{const K& operator()(const K& key){return key;}};
}class map
{struct MapKeyOfT{const K& operator()(const pair<K, V>& kv){return kv.first;}};
}
迭代器模拟
在红黑树中,迭代器是访问和遍历树节点的关键工具。下面将介绍红黑树迭代器的实现,包括如何通过迭代器遍历节点、解引用节点,以及判断两个迭代器是否相等。我们将详细讲解每个操作的实现细节,来更好理解如何高效地操作红黑树中的元素。
1. 迭代器的定义和结构
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){}// 各种操作符重载
};
-
模板参数:
- T:表示树节点存储的数据类型。
- Ref:引用类型,用于 operator* 的返回类型。
- Ptr:指针类型,用于 operator-> 的返回类型。
成员变量:
-
_node:当前迭代器指向的节点。
2. 迭代器的操作符重载
解引用操作符 operator 和箭头操作符 operator->*
Ref operator*()
{return _node->_data;
}Ptr operator->()
{return &_node->_data;
}
operator*
返回当前节点的引用,允许直接访问节点数据。operator->
返回当前节点数据的指针,允许通过指针访问节点数据成员。
不等于操作符 operator!=
bool operator!=(const Self& s)
{return _node != s._node;
}
- 用于比较两个迭代器是否指向不同的节点。
前置递增操作符 operator++
前置递增操作符 operator++
在红黑树迭代器中用于移动到下一个节点。其目的是实现节点的遍历,确保能够按顺序访问树中的元素。红黑树的迭代器在实现这个操作符时需要处理两种主要情况:
- 如果节点有右子树: 如果当前节点
_node
有右子节点,则下一个节点是其右子树中的最左子节点。 - 如果节点没有右子树: 如果当前节点没有右子节点,向上追溯父节点,直到当前节点是其父节点的左子节点,那个父节点即为后继节点。
图示讲解
假设我们有如下二叉搜索树:
示例 1:节点有右子树
假设当前节点是 6。
- 节点 6 有右子树。
- 找右子树的最左节点,即节点 7。
- 因此,节点 6 的后继节点是 7。
示例 2:节点没有右子树
假设当前节点是 5。
- 节点 5 没有右子树。
- 向上追溯父节点:
- 当前节点 5 是其父节点 3 的右子节点。
- 继续向上追溯,节点 3 是其父节点 6 的左子节点。
- 因此,节点 6 是节点 5 的后继节点。
代码:
Self& operator++()
{if (_node->_right){Node* leftMin = _node->_right;while (leftMin->_left){leftMin = leftMin->_left;}_node = leftMin;}else{Node* cur = _node;Node* parent = cur->_parent;while (parent && cur == parent->_right){cur = parent;parent = parent->_parent;}_node = parent;}return *this;
}
set模拟
我们使用红黑树来封装set,在红黑树的基础上,我们只需要对其进行简单的封装即可完成set的简单模拟。
template<class K>class set{struct SetKeyOfT{const K& operator()(const K& key){return key;}};public:typedef typename RBTree<K, const K, SetKeyOfT>::Iterator iterator;typedef typename RBTree<K, const K, SetKeyOfT>::ConstIterator const_iterator;const_iterator begin() const{return _t.Begin();}const_iterator end() const{return _t.End();}iterator begin(){return _t.Begin();}iterator end(){return _t.End();}iterator find(const K& key){return _t.Find(key);}pair<iterator, bool> insert(const K& key){return _t.Insert(key);}private:RBTree<K, const K, SetKeyOfT> _t;};
map模拟
map的实现也与set的实现类似,但注意仿函数的实现即可。
template<class K, class V>class map{struct MapKeyOfT{const K& operator()(const pair<K, V>& kv){return kv.first;}};public:typedef typename RBTree<K, pair<const K, V>, MapKeyOfT>::Iterator iterator;typedef typename RBTree<K, const K, MapKeyOfT>::ConstIterator const_iterator;const_iterator begin() const{return _t.Begin();}const_iterator end() const{return _t.End();}iterator begin(){return _t.Begin();}iterator end(){return _t.End();}iterator find(const K& key){return _t.Find(key);}pair<iterator, bool> insert(const pair<K, V>& kv){return _t.Insert(kv);}V& operator[](const K& key){pair<iterator, bool> ret = _t.Insert(make_pair(key, V()));return ret.first->second;}private:RBTree<K, pair<const K, V>, MapKeyOfT> _t;};
代码
红黑树的代码
#pragma once
#include<vector>enum Colour
{RED,BLACK
};template<class T>
struct RBTreeNode
{RBTreeNode<T>* _left;RBTreeNode<T>* _right;RBTreeNode<T>* _parent;Colour _col;T _data;RBTreeNode(const T& data):_left(nullptr), _right(nullptr), _parent(nullptr), _col(RED), _data(data){}
};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){}Ref operator*(){return _node->_data;}Ptr operator->(){return &_node->_data;}bool operator!=(const Self& s){return _node != s._node;}Self& operator++(){if (_node->_right){//下一个是右数的最左节点Node* leftMin = _node->_right;while (leftMin->_left){leftMin = leftMin->_left;}_node = leftMin;}else{Node* cur = _node;Node* parent = cur->_parent;while (parent && cur == parent->_right){cur = parent;parent = parent->_parent;}_node = parent;}return *this;}
};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*> ConstIterator;RBTree() = default;RBTree(const RBTree<K, T, KeyOfT>&t){_root = Copy(t._root);}// t2 = t1RBTree<K, T, KeyOfT>& operator=(RBTree<K, T, KeyOfT> t){swap(_root, t._root);return *this;}~RBTree(){Destroy(_root);_root = nullptr;}Iterator Begin(){Node* leftMin = _root;while (leftMin && leftMin->_left){leftMin = leftMin->_left;}return Iterator(leftMin);}Iterator End(){return Iterator(nullptr);}ConstIterator Begin() const{Node* leftMin = _root;while (leftMin && leftMin->_left){leftMin = leftMin->_left;}return ConstIterator(leftMin);}ConstIterator End() const{return ConstIterator(nullptr);}Iterator Find(const K& key){KeyOfT kot;Node* cur = _root;while (cur){if (kot(cur->_data) < key){cur = cur->_right;}else if (kot(cur->_data) > key){cur = cur->_left;}else{return Iterator(cur);}}return End();}pair<Iterator, bool>Insert(const T& data){if (_root == nullptr){_root = new Node(data);_root->_col = BLACK;return make_pair(Iterator(_root), true);}KeyOfT kot;Node* parent = nullptr;Node* cur = _root;//kot对象,用来取T类型data中的keywhile (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(Iterator(cur), false);}}cur = new Node(data);Node* newnode = cur;cur->_col = RED;if (kot(parent->_data) < kot(cur->_data)){parent->_right = cur;}else{parent->_left = cur;}cur->_parent = parent;//parent的颜色是黑色也结束while (parent && parent->_col == RED){//看叔叔Node* grandfather = parent->_parent;if (parent == grandfather->_left){Node* uncle = grandfather->_right;//如果叔叔存在,且为红if (uncle && uncle->_col == RED){parent->_col = uncle->_col = BLACK;grandfather->_col = RED;//继续向上处理cur = grandfather;parent = cur->_parent;}else//如果叔叔不在,或者是黑色{if (cur == parent->_left){// g// p u// cRotateR(grandfather);parent->_col = BLACK;grandfather->_col = RED;}else{// g// p u// cRotateL(parent);RotateR(grandfather);cur->_col = BLACK;grandfather->_col = RED;}break;}}else{Node* uncle = grandfather->_left;//叔叔存在且为红色if (uncle && uncle->_col == RED){uncle->_col = parent->_col = BLACK;grandfather->_col = RED;cur = grandfather;parent = cur->_parent;}else//叔叔不存在,或者为黑{if (cur == parent->_right){// g// u p// cRotateL(grandfather);grandfather->_col = RED;parent->_col = BLACK;}else{// g// u p// cRotateR(parent);RotateL(grandfather);grandfather->_col = RED;cur->_col = BLACK;}break;}}}_root->_col = BLACK;return make_pair(Iterator(newnode), true);}void RotateR(Node* parent){Node* SubL = parent->_left;Node* SubLR = SubL->_right;parent->_left = SubLR;if (SubLR)SubLR->_parent = parent;Node* ppNode = parent->_parent;SubL->_right = parent;parent->_parent = SubL;if (parent == _root){_root = SubL;SubL->_parent = nullptr;}else{if (ppNode->_left == parent){ppNode->_left = SubL;}else{ppNode->_right = SubL;}SubL->_parent = ppNode;}}void RotateL(Node* parent){Node* SubR = parent->_right;Node* SubRL = SubR->_left;parent->_right = SubRL;if (SubRL)SubRL->_parent = parent;Node* ppNode = parent->_parent;SubR->_left = parent;parent->_parent = SubR;if (parent == _root){_root = SubR;SubR->_parent = nullptr;}else{if (ppNode->_left == parent){ppNode->_left = SubR;}else{ppNode->_right = SubR;}SubR->_parent = ppNode;}}void InOrder(){_InOrder(_root);cout << endl;}bool IsBalance(){if (_root->_col == RED){return false;}int refNum = 0;Node* cur = _root;while (cur){if (cur->_col == BLACK){refNum++;}cur = cur->_left;}return Check(_root, 0, refNum);}private:Node* Copy(Node* root){if (root == nullptr)return nullptr;Node* newroot = new Node(root->_data);newroot->_col = root->_col;newroot->_left = Copy(root->_left);if (newroot->_left)newroot->_left->_parent = newroot;newroot->_right = Copy(root->_right);if (newroot->_right)newroot->_right->_parent = newroot;return newroot;}void Destroy(Node* root){if (root == nullptr)return;Destroy(root->_left);Destroy(root->_right);delete root;root = nullptr;}bool Check(Node* root, int blackNum, const int refNum){if (root == nullptr){if (blackNum != refNum){cout << "存在黑色节点不相等的路线" << endl;return false;}return true;}if (root->_col == BLACK){blackNum++;}if (root->_col == RED && root->_parent->_col == RED){cout << "存在连续红色节点" << endl;return false;}return Check(root->_left, blackNum, refNum)&& Check(root->_right, blackNum, refNum);}void _InOrder(Node* root){if (root == nullptr){return;}_InOrder(root->_left);// 输出数据if constexpr (std::is_same<T, std::pair<K, typename std::remove_const<K>::type>>::value){cout << root->_data.first << ":" << root->_data.second << endl;}else{cout << root->_data << endl;}_InOrder(root->_right);}Node* _root = nullptr;
};
set的代码
#pragma oncenamespace qq
{template<class K>class set{struct SetKeyOfT{const K& operator()(const K& key){return key;}};public:typedef typename RBTree<K, const K, SetKeyOfT>::Iterator iterator;typedef typename RBTree<K, const K, SetKeyOfT>::ConstIterator const_iterator;const_iterator begin() const{return _t.Begin();}const_iterator end() const{return _t.End();}iterator begin(){return _t.Begin();}iterator end(){return _t.End();}iterator find(const K& key){return _t.Find(key);}pair<iterator, bool> insert(const K& key){return _t.Insert(key);}private:RBTree<K, const K, SetKeyOfT> _t;};void PrintSet(const set<int>& s){for (auto e : s){cout << e << endl;}}void test_set(){set<int> s;s.insert(4);s.insert(2);s.insert(5);s.insert(15);s.insert(7);s.insert(1);s.insert(5);s.insert(7);PrintSet(s);set<int>::iterator it = s.begin();while (it != s.end()){//*it += 5;cout << *it << " ";++it;}cout << endl;for (auto e : s){cout << e << " ";}cout << endl;set<int> copy = s;for (auto e : copy){cout << e << " ";}cout << endl;//cout << copy._t.IsBalance() << endl;}
}
map的代码
#pragma oncenamespace qq
{template<class K, class V>class map{struct MapKeyOfT{const K& operator()(const pair<K, V>& kv){return kv.first;}};public:typedef typename RBTree<K, pair<const K, V>, MapKeyOfT>::Iterator iterator;typedef typename RBTree<K, const K, MapKeyOfT>::ConstIterator const_iterator;const_iterator begin() const{return _t.Begin();}const_iterator end() const{return _t.End();}iterator begin(){return _t.Begin();}iterator end(){return _t.End();}iterator find(const K& key){return _t.Find(key);}pair<iterator, bool> insert(const pair<K, V>& kv){return _t.Insert(kv);}V& operator[](const K& key){pair<iterator, bool> ret = _t.Insert(make_pair(key, V()));return ret.first->second;}private:RBTree<K, pair<const K, V>, MapKeyOfT> _t;};void test_map1(){map<string, int> m;m.insert({ "aa",1 });m.insert({ "basd",2 });m.insert({ "asdac",4 });m.insert({ "dsd",3 });map<string, int>::iterator it = m.begin();while (it != m.end()){//it->first += 'x';//it->second += 1;//cout << it.operator->()->first << ":" << it->second << endl;cout << it->first << ":" << it->second << endl;++it;}cout << endl;}void test_map2(){string arr[] = { "asd","qwe","sdf","cvb" };map<string, int> countMap;for (auto& e : arr){countMap[e]++;}for (auto& kv : countMap){cout << kv.first << ":" << kv.second << endl;}cout << endl;}
}