C++ set

4.set的模拟实现

首先我们要使用红黑树进行封装set即可，如下是RBTree.cpp的文件，有关红黑树的详细介绍，可以点击了解C++ 红黑树。

#include <iostream>
#include <vector>
using namespace std;
namespace rbtree
{
enum Color
{
RED,
BLACK,
};
//当我们需要存储键值对，那么T就是pair<K, V>
//当我们只存储key值，那么T就是K
template <class T>
struct RBTreeNode
{
//构造函数
RBTreeNode(T data)
:_left(nullptr)
, _right(nullptr)
, _parent(nullptr)
, _data(data)
, _col(RED)
{}
//成员变量
RBTreeNode* _left;
RBTreeNode* _right;
RBTreeNode* _parent;
T _data;//节点数据
Color _col;//颜色
};
//实现迭代器
template<class T, class Ref, class Ptr>
struct RBTreeIterator
{
typedef RBTreeNode<T> Node;
typedef RBTreeIterator<T, Ref, Ptr> Self;
Node* _node;
//构造函数
RBTreeIterator(Node* node)
:_node(node)
{}
Ref operator*()
{
return _node->_data;
}
Ptr operator->()
{
return &(_node->_data);
}
bool operator==(const Self& s)const
{
return _node == s._node;
}
bool operator!=(const Self& s)const
{
return _node != s._node;
}
//前置++
Self& operator++()
{
//如果右子树不为空，说明该树未取完，要取右子树的最左结点
if (_node->_right)
{
Node* left = _node->_right;
while (left->_left)
{
left = left->_left;
}
_node = left;
}
//右子树为空，说明该树已经取完，要回到cur为左孩子的parent
else
{
Node* cur = _node, * parent = cur->_parent;
while (parent && parent->_right == cur)
{
cur = parent;
parent = cur->_parent;
}
_node = parent;
}
return *this;
}
//后置++
Self operator++(int)
{
Self old = new Self(_node);
//如果右子树不为空，说明该树未取完，要取右子树的最左结点
if (_node->_right)
{
Node* left = _node->_right;
while (left->_left)
{
left = left->_left;
}
_node = left;
}
//右子树为空，说明该树已经取完，要回到cur为左孩子的parent
else
{
Node* cur = _node, * parent = cur->_parent;
while (parent && parent->_right == cur)
{
cur = parent;
parent = cur->_parent;
}
_node = parent;
}
return old;
}
//前置--
Self& operator--()
{
Self old = new Self(_node);
//如果左子树不为空，说明该树未取完，要取左子树的最右结点
if (_node->_left)
{
Node* right = _node->_left;
while (right->_right)
{
right = right->_right;
}
_node = right;
}
//左子树为空，说明该树已经取完，要回到cur为右孩子的parent
else
{
Node* cur = _node, * parent = cur->_parent;
while (parent && parent->_left == cur)
{
cur = parent;
parent = cur->_parent;
}
_node = parent;
}
return old;
}
//后置--
Self operator--(int)
{
//如果左子树不为空，说明该树未取完，要取左子树的最右结点
if (_node->_left)
{
Node* right = _node->_left;
while (right->_right)
{
right = right->_right;
}
_node = right;
}
//左子树为空，说明该树已经取完，要回到cur为右孩子的parent
else
{
Node* cur = _node, * parent = cur->_parent;
while (parent && parent->_left == cur)
{
cur = parent;
parent = cur->_parent;
}
_node = parent;
}
return *this;
}
};
//前面的K用于传入key的类型，后面的T用于传入红黑树存储的数据类型。
keyOfT仿函数，取出T对象中的key,用于比较
template<class K, class T, class KeyOfT>
class RBTree
{
typedef typename RBTreeNode<T> Node;
typedef typename RBTreeIterator<T, T&, T*> iterator;
public:
//构造函数
RBTree()
:_root(nullptr)
{} 
//析构函数
~RBTree()
{
Destroy(_root);
_root = nullptr;
}
iterator begin()
{
Node* left = _root;
while (left->_left)
{
left = left->_left;
}
return iterator(left);
}
iterator end()
{
return iterator(nullptr);
}

pair<iterator, bool> Insert(const T& data)
{
KeyOfT kot; 
if (_root == nullptr)
{
_root = new Node(data);
_root->_col = BLACK;
return make_pair(iterator(_root), true);
}
//找位置插入
Node* cur = _root, * parent = _root;
while (cur)
{
if (kot(data) < kot(cur->_data))
{
parent = cur;
cur = cur->_left;
}
else if (kot(data) > kot(cur->_data))
{
parent = cur;
cur = cur->_right;
}
else
{
return make_pair(iterator(cur), false);
}
}
cur = new Node(data);
cur->_parent = parent;
if (kot(data) < kot(parent->_data))
{
parent->_left = cur;
}
else
{
parent->_right = cur;
}
Node* ret = cur;
//检查颜色(当连续出现两个红色时需要调整)
while (parent && parent->_col == RED)
{
Node* grandparent = parent->_parent;
if (parent == grandparent->_left)
{
Node* uncle = grandparent->_right;
//如果uncle存在且为红，则将parent和uncle变黑，grandparent变红
if (uncle && uncle->_col == RED)
{
parent->_col = uncle->_col = BLACK;
grandparent->_col = RED;
//继续向上检查
cur = grandparent;
parent = cur->_parent;
}
//uncle不存在或者为黑
else
{
//将grandparent右旋，grandparent变为红,parent变为黑
if (cur == parent->_left)
{
RotateR(grandparent);
grandparent->_col = RED;
parent->_col = BLACK;
}
//将parent左旋，grandparent右旋，将cur变为黑，grandparent变为红
else
{
RotateL(parent);
RotateR(grandparent);
grandparent->_col =  RED;
cur->_col = BLACK;
}
//此时最上面的结点为黑，可以直接结束
break;
}
}
else
{
Node* uncle = grandparent->_left;
//如果uncle存在且为红，则将parent和uncle变黑，grandparent变红
if (uncle && uncle->_col == RED)
{
parent->_col = uncle->_col = BLACK;
grandparent->_col = RED;
//继续向上检查
cur = grandparent;
parent = cur->_parent;
}
//uncle不存在或者为黑
else
{
//将grandparent左旋，grandparent变为红,parent变为黑
if (cur == parent->_right)
{
RotateL(grandparent);
 grandparent->_col = RED;
parent->_col = BLACK;
}
//将parent右旋，grandparent左旋，将cur变为黑，grandparent变为红
else
{
RotateR(parent);
RotateL(grandparent);
grandparent->_col = RED;
cur->_col = BLACK;
}
break;
}
}
}
//把根节点变为黑
_root->_col = BLACK;
return make_pair(iterator(ret), true);
}

bool _IsRBTree(Node* root, int count, int blacknum)
{
if (root == nullptr)
{
if (count != blacknum)
{
return false;
}
return true;
}
if (root->_col == BLACK)
{
count++;
}
return _IsRBTree(root->_left, count, blacknum) &&
_IsRBTree(root->_right, count, blacknum);
}
bool IsRBTree()
{
if (_root->_col == RED)
{
return false;
}
int blacknum = 0;
Node* cur = _root;
while (cur)
{
if (cur->_col == BLACK)
{
blacknum++;
}
cur = cur->_left;
}
return _IsRBTree(_root, 0, blacknum);
}
void _InOrder(Node* root)
{
KeyOfT kot;
if (root == nullptr)
{
return;
}
_InOrder(root->_left);
cout << kot(root->_data) << " ";
_InOrder(root->_right);
}
void InOrder()
{
_InOrder(_root);
cout << endl;
}
private:
void Destroy(Node* root)
{
if (root == nullptr)
{
return;
}
Destroy(root->_left);
Destroy(root->_right);
delete root;
}
//左单旋
void RotateL(Node* parent)
{
Node* subR = parent->_right;
Node* subRL = subR->_left;
Node* grandparent = parent->_parent;
parent->_right = subRL;
if (subRL)
{
subRL->_parent = parent;
}
subR->_left = parent;
parent->_parent = subR;
if (parent == _root)
{
_root = subR;
}
else
{
if (grandparent->_left == parent)
grandparent->_left = subR;
else
grandparent->_right = subR;
}
subR->_parent = grandparent;
}
//右单旋
void RotateR(Node* parent)
{
Node* subL = parent->_left;
Node* subLR = subL->_right;
Node* grandparent = parent->_parent;
parent->_left = subLR;
if (subLR)
{
subLR->_parent = parent;
}
subL->_right = parent;
parent->_parent = subL;
if (parent == _root)
{
_root = subL;
}
else
{
if (grandparent->_left == parent)
grandparent->_left = subL;
else
grandparent->_right = subL;
}
subL->_parent = grandparent;
}
//左右双旋
void RotateLR(Node* parent)
{
Node* subL = parent->_left;
Node* subLR = subL->_right;
int bf = subLR->_bf;
RotateL(subL);
RotateR(parent);
}
//右左双旋
void RotateRL(Node* parent)
{
Node* subR = parent->_right;
Node* subRL = parent->_left;
int bf = subRL->_bf;
RotateR(subR);
RotateL(parent);
}
Node* _root;
};
};

set.cpp文件如下

#include "RBTree.cpp"
namespace lbk
{
template<class K>
class set
{
struct SetKeyOfT
{
const K& operator()(const K& key)
{
return key;
}
};
public:
typedef typename rbtree::RBTreeIterator<K, K&, K*> iterator;
iterator begin()
{
return _t.begin();
}
iterator end()
{
return _t.end();
}
pair<iterator, bool> insert(const K& key)
{
return _t.Insert(key);
}
void InOrder()
{
_t.InOrder();
}
private:
//前面的K用于传入key的类型，后面的T用于传入红黑树存储的数据类型。
//红黑树中存储的值不可以改变，应加上const
rbtree::RBTree<K, const K, SetKeyOfT> _t;
};
};