C++map和set的实现
·
一、map和set的实现
实现STL中的map与set底层使用的是map和set
1.1底层红黑树的实现（RBTree.h）：
#pragma once
#include<iostream>
#include<set>
#include<assert.h>
#include<stdbool.h>
#include<time.h>
#include<vector>
#include<string>
using namespace std;
enum color
{
RED,
BLACK
};
template<typename T>
class RBTreeNode
{
public:
RBTreeNode<T>* _left;
RBTreeNode<T>* _right;
RBTreeNode<T>* _parent;
T _data;
color _color;
RBTreeNode(const T& data)
:_left(nullptr)
, _right(nullptr)
, _parent(nullptr)
, _data(data)
, _color(RED)
{
}
};
template<class T, class Ptr, class Ref>
struct __TreeIterator
{
typedef RBTreeNode<T> Node;
typedef __TreeIterator<T, Ptr, Ref> self;
typedef __TreeIterator<T, T*, T&> iterator;
Node* _node;
__TreeIterator(Node* node)
:_node(node)
{
}
__TreeIterator(const iterator& it)
:_node(it._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;
}
self& operator--()
{
//左子树存在
if (_node->_left)
{
//找左子树的最右侧结点
Node* rightmost = _node->_left;
while (_node->_right)
{
rightmost = rightmost->_right;
}
_node = rightmost;
}
else//左子树不存在
{
Node* cur = _node;
Node* parent = _node->_parent;
//要找到孩子是父亲右的那个结点
while (parent && cur == parent->_left)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
self& operator++()//两种情况：1、右节点存在 2、右节点不存在
{
if (_node->_right)//右节点存在
{
//此时要访问右树的最左边结点
Node* leftmost = _node;
while (leftmost->_left)
{
leftmost = leftmost->_left;
}
_node = leftmost;
}
else//右节点不存在
{
//此时要访问这个结点的父亲结点
Node* cur = _node;
Node* parent = cur->_parent;
while (parent && cur = parent->_right)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
};
template<typename K, typename T, class KeyOfT>
class RBTree
{
public:
typedef RBTreeNode<T> Node;
//这里的iterator和const_iterator是同一个类模板，传的不同的参数实例化出的不同类型
typedef __TreeIterator<T, T*, T&> iterator;
typedef __TreeIterator<T, const T*, const T&> const_iterator;
//迭代器
iterator begin()
{
Node* leftmost = _root;
while (leftmost && leftmost->_left)
{
leftmost = leftmost->_left;
}
return iterator(leftmost);
}
iterator end()
{
return iterator(nullptr);
}
const_iterator begin() const
{
Node* leftmost = _root;
while (leftmost && leftmost->_left)
{
leftmost = leftmost->_left;
}
return const_iterator(leftmost);
}
const_iterator end() const
{
return const_iterator(nullptr);
}
//查找
Node* Find(const K& key)
{
Node* cur = _root;
KeyOfT kt;
while (cur)
{
if (kt(cur->_data) < key)
{
cur = cur->_right;
}
else if (kt(cur->_data) > key)
{
cur = cur->_left;
}
else
{
return cur;
}
}
return nullptr;
}
//插入
pair<iterator,bool> Insert(const T& data )//这里的T是key就是set，key是pair就是map
{
if (_root == nullptr)
{
_root = new Node(data);
_root->_color = BLACK;//根节点设置成黑色
return make_pair(iterator(_root), true);
}
Node* cur = _root;
Node* parent = nullptr;
//把key取出来
KeyOfT kt;
while (cur)
{
if (kt(cur- >_data) < kt(data))
{
parent = cur;
cur = cur->_right;
}
else if (kt(cur->_data) > kt(data))
{
parent = cur;
cur = cur->_left;
}
else
{
//返回已经有的这个结点的迭代器
return make_pair(iterator(cur), false);
}
}
cur = new Node(data);
Node* newnode = cur;
cur->_color = RED;//把除根节点以外的节点首次设置成红色
//把新结点链接到上一个结点的后面
if (kt(parent->_data) < kt(data))
{
parent->_right = cur;
}
else if (kt(parent->_data) > kt(data))
{
parent->_left = cur;
}
else
{
assert(false);
}
cur->_parent = parent;
//对颜色进行调节
while (parent && parent->_color == RED)
{
Node* grandfather = parent->_parent;
if (parent == grandfather->_left)
{
Node* uncle = grandfather->_right;
if (uncle && uncle->_color == RED)//uncle存在且为红色
{
//变色处理
uncle->_color = BLACK;
parent->_color = BLACK;
grandfather->_color = RED;
//继续向上处理
cur = grandfather;
parent = cur->_parent;
}
else//uncle不存在或者uncle为黑色
{
if (cur == parent->_left)//cur在parent左边，进行单旋
{
//对grandfather进行右旋
RotateR(grandfather);
//对parent和grandfather进行颜色的更改
parent->_color = BLACK;
grandfather->_color = RED;
}
else//cur在parent的右边，进行双旋
{
//先对parent进行左旋
RotateL(parent);
//在对grandfather进行右旋
RotateR(grandfather);
grandfather->_color = RED;
cur->_color = BLACK;
}
break;
}
}
else//parent在grandfather的右边
{
Node* uncle = grandfather->_left;
if (uncle && uncle->_color == RED)//uncle存在且uncle为红色
{
//变色处理
parent->_color = BLACK;
grandfather->_color = RED;
uncle->_color = BLACK;
//继续向上处理
cur = grandfather;
parent = cur->_parent;
}
else//uncle不存在或者uncle为黑色
{
if (cur == parent->_right)//cur在parent的右边（cur和pg在一条直线上）
{
//向左进行旋
RotateL(grandfather);
//颜色处理
parent->_color = BLACK;
grandfather->_color = RED;
}
else//cur在parent的左边
{
//先进行右旋
RotateR(parent);
//在进行左旋
RotateL(grandfather);
cur->_color = BLACK;
grandfather->_color = RED;
}
break;
}
}
}
_root->_color = BLACK;
return make_pair(iterator(newnode), true);
}
//左单旋
void RotateL(Node* parent)
{
Node* cur = parent->_right;
Node* curleft = cur->_left;
parent->_right = curleft;
if (curleft)
{
curleft->_parent = parent;
}
cur->_left = parent;
Node* ppnode = parent->_parent;
parent->_parent = cur;
if (parent == _root)
{
_root = cur;
cur->_parent = nullptr;
}
else
{
if (ppnode->_left == parent)
{
ppnode->_left = cur;
}
else
{
ppnode->_right = cur;
}
cur->_parent = ppnode;
}
}
//右单旋
void RotateR(Node* parent)
{
Node* cur = parent->_left;
Node* curright = cur->_right;
parent->_left = curright;
if (curright)
curright->_parent = parent;
Node* ppnode = parent->_parent;
cur->_right = parent;
parent->_parent = cur;
if (ppnode == nullptr)
{
_root = cur;
cur->_parent = nullptr;
}
else
{
if (ppnode->_left == parent)
{
ppnode->_left = cur;
}
else
{
ppnode->_right = cur;
}
cur->_parent = ppnode;
}
}
//红黑树判断是否平衡
bool CheckColor(Node* root, int blacknum, int benchmark)//此处不加引用算的是每条路径上的节点数量
{
if (root == nullptr)
{
if (blacknum != benchmark)
{
return false;
}
return true;
}
if (root->_color == BLACK)
{
++blacknum;
}
if (root->_color == RED && root->_parent && root->_parent->_color == RED)
{
cout << "root->_kv.first" << "出现连续的红色结点" << endl;
return false;
}
return CheckColor(root->_left, blacknum, benchmark) && CheckColor(root->_right, blacknum, benchmark);
}
bool _IsBalance()
{
return IsBalance(_root);
}
bool IsBalance(Node* root)
{
if (root == nullptr)
{
return true;
}
//检查根节点是否为黑色
if (root->_color != BLACK)
{
return false;
}
//求出最左路径作为基准值
int benchmark = 0;
Node* cur = root;
while (cur)
{
if (cur->_color == BLACK)
{
++benchmark;
}
cur = cur->_left;
}
//检查是否右连续的红色结点
return CheckColor(root, 0, benchmark);
}
//求高度
int Height()
{
return Height(_root);
}
int Height(Node* root)
{
if (root == nullptr)
return 0;
int leftHeight = Height(root->_left);
int rightHeight = Height(root->_right);
return leftHeight > rightHeight ? leftHeight + 1 : rightHeight + 1;
}
protected:
Node* _root = nullptr;
};1.2map和set的实现：
1.2.1map的实现（My_Map.h)：
#pragma once
#include"RBTree.h"
namespace my_map
{
template<typename K, class V>
class map
{
public:
struct MapKeyOfT
{
const K& operator()(const pair<K, V>& kv)
{
return kv.first;
}
};
typedef typename RBTree<K, pair<const K, V>, MapKeyOfT>::iterator iterator;
typedef typename RBTree<K, pair<const K, V>, MapKeyOfT>::const_iterator const_iterator;
iterator begin()
{
return _t.begin();
}
iterator end()
{
return _t.end();
}
const_iterator begin() const
{
return _t.begin();
}
const_iterator end() const
{
return _t.end();
}
//插入
pair<iterator,bool> insert(const pair<K, V>& kv)
{
return _t.Insert(kv);
}
V& operator[](const K& key)
{
pair<iterator, bool> ret = insert(make_pair(key), V());
return ret.first->second;
}
protected:
RBTree<K, pair<const K, V>, MapKeyOfT> _t;
};
}1.2.2set的实现(My_Set.h):
#pragma once
#include "RBTree.h"
namespace my_set
{
template<typename K>
class set
{
struct SetKeyOfT
{
const K& operator()(const K& key)
{
return key;
}
};
public:
//类模板里取内嵌类型加typename
typedef typename RBTree<K, K, SetKeyOfT>::const_iterator iterator;
typedef typename RBTree<K, K, SetKeyOfT>::const_iterator const_iterator;
iterator begin()
{
return _t.begin();
}
iterator end()
{
return _t.end();
}
const_iterator begin() const
{
return _t.begin();
}
const_iterator end() const
{
return _t.end();
}
//插入
pair<iterator,bool> insert(const K& key)
{
pair< typename RBTree<K, K, SetKeyOfT>::iterator, bool> ret = _t.Insert(key);
return pair<iterator, bool>(ret.first, ret.second);
//return中pair里面的iterator是const_iterator
}
protected:
RBTree<K, K, SetKeyOfT> _t;
};
}二、模拟实现的map和set进行测试
#include "My_Map.h"
#include "My_Set.h"
int main()
{
//set测试
my_set::set<int> s1;
s1.insert(2);
s1.insert(5);
s1.insert(8);
my_set::set<int>::iterator it1 = s1.begin();
while (it1 != s1.end())
{
cout << *it1 << " ";
++it1;
}
cout << endl;
//范围for
for (const auto& element : s1)
{
cout << element;
}
cout << endl;
//map测试
my_map::map<string, string> dict;
dict.insert(make_pair("love", "爱"));
dict.insert(make_pair("insert", "插入"));
dict.insert(make_pair("miss", "错过、想念"));
my_map::map<string, string>::iterator it2 = dict.begin();
while (it2 != dict.end())
{
cout << it2->first << ":" << it2->second;
++it2;
}
cout << endl;
//范围for
for (const auto& element : dict)
{
cout << element.first << ":" << element.second;
}
cout << endl;
my_map::map<string, int> countmap;
countmap["西瓜"];//插入
countmap["冬瓜"] = 1;//插入+修改
countmap["西瓜"] = 2;//修改
return 0;
}
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