一、前情回顾
set 参数只有 key,但是map除了key还有value。我们还是需要KV模型的红黑树的:
#pragma once
#include <iostream>
#include <assert.h>
#include <time.h>
using namespace std;
enum Color
{
RED,
BLACK,
};
template<class K, class V >
struct RBTreeNode
{
pair<K, V> _kv;
RBTreeNode<K, V>* _left;
RBTreeNode<K, V>* _right;
RBTreeNode<K, V>* _parent;
Color _col;
RBTreeNode(const pair<K,V>& kv)
:_kv(kv)
,_left(nullptr)
,_right(nullptr)
,_parent(nullptr)
,_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;
if (parent->_kv.first < kv.first)
{
parent->_right = cur;
cur->_parent = parent;
}
else
{
parent->_left = cur;
cur->_parent = parent;
}
while (parent && parent->_col == RED)
{
Node* grandfater = parent->_parent;
if (parent == grandfater->_left)
{
Node* uncle = grandfater->_right;
//情况一:u存在且为红
if (uncle && uncle->_col == RED)
{
parent->_col = uncle->_col = BLACK;
grandfater->_col = RED;
//向上调整
cur = grandfater;
parent = cur->_parent;
}
else
{
//情况2
if (cur == parent->_left)
{
RotateR(grandfater);
parent->_col = BLACK;
grandfater->_col = RED;
}
//情况3
else
{
// g
// p
// c
RotateL(parent);
RotateR(grandfater);
cur->_col = BLACK;
grandfater->_col = RED;
}
break;
}
}
else//parent==grandfater->_right
{
Node* uncle = grandfater->_left;
//情况1:u存在且为红色
if (uncle && uncle->_col == RED)
{
uncle->_col = parent->_col = BLACK;
grandfater->_col = RED;
//向上调整
cur = grandfater;
parent = cur->_parent;
}
else
{
//情况2:u不存在/u存在为黑色
//g
// p
// c
if (cur == parent->_right)
{
RotateL(grandfater);
grandfater->_col = RED;
parent->_col = BLACK;
}
//情况3
// g
// p
// c
else
{
RotateR(parent);
RotateL(grandfater);
cur->_col = BLACK;
grandfater->_col = RED;
}
break;
}
}
}
//根变黑
_root->_col = BLACK;
return true;
}
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 (ppNode == nullptr)
{
_root = subR;
_root->_parent = nullptr;
}
else
{
if (ppNode->_left == parent)
{
ppNode->_left = subR;
}
else
{
ppNode->_right = subR;
}
subR->_parent = ppNode;
}
}
void RotateR(Node* parent)
{
Node* subL = parent->_left;
Node* subLR = subL->_right;
parent->_left = subLR;
if (subLR)
subLR->_parent = parent;
Node* ppNode = parent->_parent;
parent->_parent = subL;
subL->_right = parent;
if (ppNode == nullptr)
{
_root = subL;
_root->_parent = nullptr;
}
else
{
if (ppNode->_left == parent)
{
ppNode->_left = subL;
}
else
{
ppNode->_right = subL;
}
subL->_parent = ppNode;
}
}
void InOrder()
{
_InOrder(_root);
}
void _InOrder(Node* root)
{
if (root == nullptr)
return;
_InOrder(root->_left);
cout << root->_kv.first << ":" << root->_kv.second << endl;
_InOrder(root->_right);
}
bool Check(Node*root,int blackNum,int ref)
{
if (root == nullptr)
{
//cout << blackNum << endl;
if (blackNum != ref)
{
cout << "违反规则:本条路径的黑色结点的数量根最左路径不相等" << endl;
return false;
}
return true;
}
if (root->_col == RED && root->_parent->_col == RED)
{
cout << "违反规则:出现连续的红色结点" << endl;
return false;
}
if (root->_col == BLACK)
{
++blackNum;
}
return Check(root->_left,blackNum,ref)
&& Check(root->_right,blackNum,ref);
}
bool IsBalance()
{
if (_root == nullptr)
{
return true;
}
if (_root->_col != BLACK)
{
return false;
}
int ref = 0;
Node* left = _root;
while (left)
{
if (left->_col == BLACK)
{
++ref;
}
left = left->_left;
}
return Check(_root,0,ref);
}
private:
Node* _root = nullptr;
};
二、简化源码
翻开源码一看📕
RBTree的结构源码:是KV结构的红黑树
RBTree是通过传入的Value的值来判断类型,也就是一棵泛型的RBTree,通过不同的实例化,实现出了Map和Set:
对于map:传key,对于set:传pair
map的结构简化源码
:
set的结构简化源码
:
为了让我们的红黑树能够识别set与map我们增加一个模板参数T:
template<class K, class T>
class RBTree
对于T模板参数可能是键值Key,也可能是由Key和Value共同构成的键值对。
如果是set容器,那么它传入底层红黑树的模板参数就是Key和Key:
template<class K>
class set
{
private:
RBTree<K,K> _t;
};
如果是map容器,传入底层红黑树的模板参数就是Key和Key和value的键值对:
class map
{
private:
RBTree<K, pair<const K,V>> _t;
};
通过上面,我们可以知道,对于set和map的区别:我们只要通过第二个模板参数就能进行区分,那是不是第一个模板参数就没有意义了呢?
对于insert(const Value&v)来说,需要放入存入的值,确实是这个样子的,插入的值是value,对于set就是key,对于map就是pair。
但是对于find(const Key&key)来说,查找的参数不是value,找的不是pair而是Key,对于map容器来说就不行了。
**红黑树的节点**
:set容器:K和T都是键值Key; map容器:K是键值Key,T由Key和Value构成的键值对;但是底层红黑树并不知道上层容器到底是map还是set,因此红黑树的结点当中直接存储T就行了,如果是set的时候,结点当中存储的是键值Key;如果是map的时候,结点当中存储的就是键值对,所以红黑树的结点定义如下,由T类型来决定红黑树存的是key还是pair:
template<class T>
//三叉链结构
struct RBTreeNode
{
T _data;
RBTreeNode<T>* _left;
RBTreeNode<T>* _right;
RBTreeNode<T>* _parent;
Color _col;
RBTreeNode(const T& data)
:_data(data)
, _left(nullptr)
, _right(nullptr)
, _parent(nullptr)
, _col(RED)
{}
};
三、仿函数
这里存在一个问题📝:插入的时候data的大小如何去进行比较:我们并不知道是什么类型是key,还是pair的比较,而我们刚开始kv结构就直接用kv.first去比较了。
对于set是
Key
,可以比较对于map是
pair
,那我们要取其中的first来比较,但是pair的大小并不是直接按照first去进行比较的,而我们只需要按照first去进行比较
由于底层的红黑树不知道传的是map还是set容器,当需要进行两个结点键值的比较时,底层红黑树传入的仿函数来获取键值Key,进行两个结点键值的比较:这个时候我们就需要仿函数了,如果是set那就是用于返回T当中的键值Key,如果是map那就是用于返回pair的first:
仿函数/函数对象也是类,是一个类对象。仿函数要重载operator()。
namespace HWC
{
template<class K,class V>
class map
{
struct MapKeyOfT
{
const K& operator()(const pair<const K, V>& kv)
{
return kv.first;
}
};
public:
private:
RBTree<K, pair<const K,V>,MapKeyOfT> _t;
};
namespace HWC
{
template<class K>
class set
{
struct SetKeyOfT
{
const K& operator()(const K& key)
{
return key;
}
};
private:
RBTree<K,K,SetKeyOfT> _t;
};
博主画了个图更加容易进行比对👇
查找过程,此时就可以套上我们所写的仿函数对象去进行数据的大小比较了:
KeyOfT kot;//仿函数对象
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 false;
}
}
四、迭代器
红黑树的正向迭代器是对结点指针进行了封装,所以这里的正向迭代器就只有一个成员变量:结点的指针,并没有什么其他的地方,迭代器的定义:
template<class T,class Ref,class Ptr>
struct __RBTreeIterator
{
typedef RBTreeNode<T> Node;
typedef __RBTreeIterator<T,Ref,Ptr> Self;
typedef __RBTreeIterator<T, T&, T*> iterator;
Node* _node;
__RBTreeIterator(Node*node)
:_node(node)
{}
//普通迭代器的时候,它是拷贝构造
//const迭代器的时候,它是构造,支持用普通迭代器构造const迭代器
__RBTreeIterator(const iterator& s)
:_node(s._node)
{}
}
*:解引用操作,返回对应结点数据的引用:
Ref operator*()
{
return _node->_data;
}
->:成员访问操作符,返回结点数据的引用:
Ptr operator->()
{
return &_node->_data;
}
!=、==:比较简单
bool operator !=(const Self & s) const
{
return _node != s._node;
}
bool operator ==(const Self& s) const
{
return _node == s._node;
}
这里的迭代器重点是迭代器的++
:
一个结点的正向迭代器进行++
操作后,根据红黑树中序(左、根、右)找到当前结点的下一个结点,中序的第一个节点是最左,迭代器的++
怎么去找:
如果节点的右子树不为空,++
就是找右子树的最左节点
如果节点的右子树为空,++
就是找祖先(孩子是父亲的左的那个祖先)
代码实现✍
:
Self& operator++()
{
if (_node->_right)
{
Node* min = _node->_right;
while (min->_left)
{
min = min->_left;
}
_node = min;
}
else
{
Node* cur = _node;
Node* parent = cur->_parent;
while (parent && cur == parent->_right)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
迭代器的--
对于–,如果是根,–就是左子树,找到左子树最大的那一个(最右节点)
如果节点的左子树不为空,--
找左子树最右的节点
如果节点的左子树为空,--
找祖先(孩子是父亲的右的祖先)
代码实现✍
:
Self& operator--()
{
if (_node->_left)
{
Node* max = _node->_left;
while (max->_right)
{
max = max->_right;
}
_node = max;
}
else
{
Node* cur = _node;
Node* parent = cur->_parent;
while (parent&&cur==parent->_left)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
不要忘记迭代器的两个核心成员:begin()与end()
begin()
:返回中序(左、根、右)第一个结点的正向迭代器,即最左节点,返回的是最左节点,直接找最左节点即可
end()
:返回中序(左、根、右)最后一个结点下一个位置的正向迭代器,这里直接用空指针
template<class K, class T,class KeyOfT>
class RBTree
{
typedef RBTreeNode<T> Node;
public:
typedef __RBTreeIterator<T> iterator;
iterator begin()
{
Node* left = _root;
while (left && left->_left)
{
left = left->_left;
}
return iterator(left);
}
iterator end()
{
return iterator(nullptr);
}
}
五、set的实现
通过前面底层红黑树的接口进行套用即可实现set的实现:
值得注意的是🔴:typename:没有实例化的模板,区分不了是静态变量还是类型,typename告诉编译器是类型
#pragma once
#include "RBTree.h"
namespace hwc
{
template <class K>
class set
{
struct SetKeyOfT
{
const K& operator()(const K& key)
{
return key;
}
};
public:
//typename:没有实例化的模板,区分不了是静态变量还是类型,typename告诉编译器是类型
typedef typename RBTree<K, K, SetKeyOfT>::const_iterator iterator;//key不可以修改
typedef typename RBTree<K, K, SetKeyOfT>::const_iterator const_iterator;
iterator begin() const
{
return _t.begin();
}
iterator end() const
{
return _t.end();
}
pair<iterator,bool> insert(const K& key)
{
//底层红黑树的iterator是普通迭代器
pair<typename RBTree<K, K, SetKeyOfT>::iterator, bool> ret = _t.Insert(key);
return pair<iterator, bool>(ret.first, ret.second);//用普通迭代器构造const迭代器
}
private:
RBTree<K, K,SetKeyOfT> _t;
};
void test_set()
{
int a[] = { 4, 2, 6, 1, 3, 5, 15, 7, 16, 14 };
set<int> s;
for (auto e : a)
{
s.insert(e);
}
set<int>::iterator it = s.begin();
while (it != s.end())
{
cout << *it << " ";
++it;
}
cout << endl;
for (auto e : s)
{
cout << e << " ";
}
cout << endl;
}
}
六、map的实现
同样是套用上底层红黑树的接口,不过map的实现有一个很重要的地方,那就是[]的实现
#pragma once
#include "RBTree.h"
namespace hwc
{
template<class K,class V>
class map
{
struct MapkeyOfT
{
const K& operator()(const pair<const K, V>& kv)
{
return kv.first;
}
};
public:
//typename:没有实例化的模板,区分不了是静态变量还是类型,typename告诉编译器是类型
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();
}
pair<iterator,bool> insert(const pair<const 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;
}
private:
RBTree<K, pair<const K, V>, MapkeyOfT> _t;
};
void test_map()
{
int a[] = { 4, 2, 6, 1, 3, 5, 15, 7, 16, 14 };
map<int, int> m;
for (auto e : a)
{
m.insert(make_pair(e, e));
}
map<int, int>::iterator it = m.begin();
while(it!=m.end())
{
it->second++;
cout << it->first << ":" << it->second << endl;
++it;
}
cout << endl;
map<string, int> countMap;
string arr[] = { "苹果","西瓜","香蕉","苹果"};
for (auto& e : arr)
{
countMap[e]++;
}
for (auto& kv : countMap)
{
cout << kv.first << ":" << kv.second << endl;
}
}
}
七、红黑树代码
最后,在这里送上源码:
#pragma once
#pragma once
#include <iostream>
#include <assert.h>
#include <time.h>
using namespace std;
enum Color
{
RED,
BLACK,
};
template<class T>
struct RBTreeNode
{
T _data;
RBTreeNode<T>* _left;
RBTreeNode<T>* _right;
RBTreeNode<T>* _parent;
Color _col;
RBTreeNode(const T& data)
:_data(data)
, _left(nullptr)
, _right(nullptr)
, _parent(nullptr)
, _col(RED)
{}
};
template<class T,class Ref,class Ptr>
struct __RBTreeIterator
{
typedef RBTreeNode<T> Node;
typedef __RBTreeIterator<T,Ref,Ptr> Self;
typedef __RBTreeIterator<T, T&, T*> iterator;
Node* _node;
__RBTreeIterator(Node*node)
:_node(node)
{}
//普通迭代器的时候,它是拷贝构造
//const迭代器的时候,它是构造,支持用普通迭代器构造const迭代器
__RBTreeIterator(const iterator& s)
:_node(s._node)
{}
Ref operator*()
{
return _node->_data;
}
Ptr operator->()
{
return &_node->_data;
}
Self& operator++()
{
if (_node->_right)
{
Node* min = _node->_right;
while (min->_left)
{
min = min->_left;
}
_node = min;
}
else
{
Node* cur = _node;
Node* parent = cur->_parent;
while (parent && cur == parent->_right)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
Self& operator--()
{
if (_node->_left)
{
Node* max = _node->_left;
while (max->_right)
{
max = max->_right;
}
_node = max;
}
else
{
Node* cur = _node;
Node* parent = cur->_parent;
while (parent&&cur==parent->_left)
{
cur = cur->_parent;
parent = parent->_parent;
}
_node = parent;
}
return *this;
}
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;
const_iterator begin() const
{
Node* left = _root;
while (left && left->_left)
{
left = left->_left;
}
return const_iterator(left);
}
const_iterator end() const
{
return const_iterator(nullptr);
}
iterator begin()
{
Node* left = _root;
while (left && left->_left)
{
left = left->_left;
}
return iterator(left);
}
iterator end()
{
return iterator(nullptr);
}
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;
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(iterator(cur),false);
}
}
cur = new Node(data);
Node* newnode = cur;
cur->_col = RED;
if (kot(parent->_data) < kot(data))
{
parent->_right = cur;
cur->_parent = parent;
}
else
{
parent->_left = cur;
cur->_parent = parent;
}
while (parent && parent->_col == RED)
{
Node* grandfater = parent->_parent;
if (parent == grandfater->_left)
{
Node* uncle = grandfater->_right;
//情况一:u存在且为红
if (uncle && uncle->_col == RED)
{
parent->_col = uncle->_col = BLACK;
grandfater->_col = RED;
//向上调整
cur = grandfater;
parent = cur->_parent;
}
else
{
//情况2
if (cur == parent->_left)
{
RotateR(grandfater);
parent->_col = BLACK;
grandfater->_col = RED;
}
//情况3
else
{
// g
// p
// c
RotateL(parent);
RotateR(grandfater);
cur->_col = BLACK;
grandfater->_col = RED;
}
break;
}
}
else//parent==grandfater->_right
{
Node* uncle = grandfater->_left;
//情况1:u存在且为红色
if (uncle && uncle->_col == RED)
{
uncle->_col = parent->_col = BLACK;
grandfater->_col = RED;
//向上调整
cur = grandfater;
parent = cur->_parent;
}
else
{
//情况2:u不存在/u存在为黑色
//g
// p
// c
if (cur == parent->_right)
{
RotateL(grandfater);
grandfater->_col = RED;
parent->_col = BLACK;
}
//情况3
// g
// p
// c
else
{
RotateR(parent);
RotateL(grandfater);
cur->_col = BLACK;
grandfater->_col = RED;
}
break;
}
}
}
//根变黑
_root->_col = BLACK;
return make_pair(iterator(newnode),true);
}
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 (ppNode == nullptr)
{
_root = subR;
_root->_parent = nullptr;
}
else
{
if (ppNode->_left == parent)
{
ppNode->_left = subR;
}
else
{
ppNode->_right = subR;
}
subR->_parent = ppNode;
}
}
void RotateR(Node* parent)
{
Node* subL = parent->_left;
Node* subLR = subL->_right;
parent->_left = subLR;
if (subLR)
subLR->_parent = parent;
Node* ppNode = parent->_parent;
parent->_parent = subL;
subL->_right = parent;
if (ppNode == nullptr)
{
_root = subL;
_root->_parent = nullptr;
}
else
{
if (ppNode->_left == parent)
{
ppNode->_left = subL;
}
else
{
ppNode->_right = subL;
}
subL->_parent = ppNode;
}
}
void InOrder()
{
_InOrder(_root);
}
void _InOrder(Node* root)
{
if (root == nullptr)
return;
_InOrder(root->_left);
cout << root->_kv.first << ":" << root->_kv.second << endl;
_InOrder(root->_right);
}
bool Check(Node* root, int blackNum, int ref)
{
if (root == nullptr)
{
//cout << blackNum << endl;
if (blackNum != ref)
{
cout << "违反规则:本条路径的黑色结点的数量根最左路径不相等" << endl;
return false;
}
return true;
}
if (root->_col == RED && root->_parent->_col == RED)
{
cout << "违反规则:出现连续的红色结点" << endl;
return false;
}
if (root->_col == BLACK)
{
++blackNum;
}
return Check(root->_left, blackNum, ref)
&& Check(root->_right, blackNum, ref);
}
bool IsBalance()
{
if (_root == nullptr)
{
return true;
}
if (_root->_col != BLACK)
{
return false;
}
int ref = 0;
Node* left = _root;
while (left)
{
if (left->_col == BLACK)
{
++ref;
}
left = left->_left;
}
return Check(_root, 0, ref);
}
private:
Node* _root = nullptr;
};
本篇结束…