1.对红黑树进行改造
1.1treenode模板参数改变
之前构建treenode模板参数传的是class k,class v(set为k,k;map是k,v),现在直接用T代替
template<class T> //这里直接传了T作为模板参数,T可能是pair<k,t>,也可能是k
struct RBTtreenode
{RBTtreenode<T>* _left;RBTtreenode<T>* _right;RBTtreenode<T>* _parent;//pair<K, V> kv;T data;color col;RBTtreenode(const T& _data):_left(nullptr), _right(nullptr), _parent(nullptr), data(_data), col(RED){}
};
2.构建红黑树的迭代器
因为要构建const_iterator(不可修改内容) 和iterator(可修改内容)所以需要三个模板参数
//<T,T&,T*> iterator;//普通迭代器
//<T, const T&, const T*> const_iterator;//指向的东西不能改变template<class T,class Ref,class Ptr>
iterator内存的是node*类型的数据!!!!
2.1 重载operator*() (set)
因为set传模板参数只传K,没有V,data类型是K,
所以用*直接取得data即可
Ref operator*()
{return _node->data;
}
2.2 重载operator->() (map)
因为map模板参数传的是K,pair<const K,T>,data类型是pair<const K,T>,
想取到K,则需要传回&data,再用->first取得K
Ptr operator->()
{return &_node->data;
}
2.3operator++()与operator--()
这里以operator++()做解释:
分三种情况:
1.如果右子树不为空,则找到右子树的最左节点
2.//如果右子树为空,且cur是parent的右子树,则先parent回溯至parent->_parent,再_node变为parent
3.//如果右子树为空,且cur是parent的左子树,则_node变为parent
iterator& operator++()
{if (_node->_right){//如果右子树不为空,则找到右子树的最左节点node* cur = _node->_right;while (cur && cur->_left){cur = cur->_left;}_node = cur;}else{//如果右子树为空,且cur是parent的右子树,则先parent回溯至parent->_parent,再_node变为parent//如果右子树为空,且cur是parent的左子树,则_node变为parentnode* cur = _node;node* parent = cur->_parent;while (parent && cur == parent->_right){cur = parent;parent = parent->_parent;}_node = parent;}return *this;
}
2.4.begin()&&end()
iterator begin()
{node* flag = root;while (flag&&flag->_left)//flag可能为nullptr{flag = flag->_left;}return iterator(flag);
}iterator end()
{return iterator(nullptr); //end用nullptr去构造!!!!!!!!
}const_iterator begin() const
{node* flag = root;while (flag && flag->_left)//flag可能为nullptr{flag = flag->_left;}return const_iterator(flag);
}const_iterator end() const
{return const_iterator(nullptr); //end用nullptr去构造!!!!!!!!
}
3.set.h封装
https://cplusplus.com/reference/set/set/?kw=set
#include"rbt.h"
namespace zone
{template<class K>class set{public:struct setkeyoft //仿函数,用来取出红黑树节点data中的key{const K& operator()(const K& key){return key;}};//set这里的迭代器本质都是const_iterator,因为k要求无法修改typedef typename RBTtree<K, K, setkeyoft>::const_iterator iterator;//记得要使用typename告诉编译器RBTtree<K, K, setkeyoft>::iterator这个是类型,不是函数typedef typename RBTtree<K, K, setkeyoft>::const_iterator const_iterator;iterator begin()const{return it.begin();}iterator end()const{return it.end();}pair<iterator,bool> insert(const K& key){return it.insert(key);}void inorder(){it.inorder();}private:RBTtree<K,K,setkeyoft> it;};
}
3.1 仿函数setkeyoft
仿函数,用来取出红黑树节点data中的key,用于insert函数!!!!
3.2 iterator和const_iterator
//set这里的迭代器本质都是const_iterator,因为k要求无法修改
typedef typename RBTtree<K, K, setkeyoft>::const_iterator iterator;
typedef typename RBTtree<K, K, setkeyoft>::const_iterator const_iterator;
4.map.h封装
https://cplusplus.com/reference/map/map/?kw=map
#include"rbt.h"
namespace zone
{template<class K,class T>class map{public:struct setkeyoft{const K& operator()(const pair<K, T>& key){return key.first;}};//map这里的迭代器则使用的是iterator,因为k要求无法修改,但v可以修改,所以可以直接初始化时用pair<const K, T>typedef typename RBTtree<K, pair<const K, T>, setkeyoft>::iterator iterator;typedef typename RBTtree<K, pair<const K, T>, setkeyoft>::const_iterator const_iterator;pair<iterator, bool> insert(const pair<K, T>& key){return it.insert(key);}T& operator[](const K& key){pair<iterator, bool>ret = insert(make_pair(key,T()));//insert返回一个pair,first是iterator,second是bool类型return ret.first->second;}iterator begin(){return it.begin();}iterator end(){return it.end();}void inorder(){it.inorder();}private:RBTtree<K,pair<const K,T>, setkeyoft> it;};
}
5.insert函数 !!!!!!!
RBT.h里insert函数的返回值是 pair<node*, bool>
但封装过后的map.h,set.h里
pair<iterator,bool> insert(const K& key) {return it.insert(key); }
返回值是pair<iterator,bool>
可见 pair<node*, bool>和pair<iterator(这里的iterator已经重命名了,本质是const_iteratir),bool>并不是同一类型,该如何解决呢?
1.如果T1和U类型一致,T2和V类型一致,那么就是拷贝构造!!!
2.如果不一致,也可以进行普通构造,前提是有可以用first来构建T1的函数!!!!!
回到刚才的问题:
可见 pair<node*, bool>和pair<iterator(这里的iterator已经重命名了,本质是const_iteratir),bool>并不是同一类型,该如何解决呢?
bool类型肯定可以用bool类型初始化,
iterator可以用node*进行初始化吗?
答案是可以的
treeiterator(node* it):_node(it) {}
相当于使用了隐式类型转换
6.杂谈
类比指针:
1.iterator 可修改指向的数据,也可改变自身
2.const iterator 可修改指向的数据,但不可改变自身
3.const_iterator 不可修改指向的数据,但能改变自身
7.代码全览
RBT.h
#include<iostream>using namespace std;enum color
{RED,BLACK
}; //列举color的各种可能情况template<class T> //这里直接传了T作为模板参数,T可能是pair<k,t>,也可能是k
struct RBTtreenode
{RBTtreenode<T>* _left;RBTtreenode<T>* _right;RBTtreenode<T>* _parent;//pair<K, V> kv;T data;color col;RBTtreenode(const T& _data):_left(nullptr), _right(nullptr), _parent(nullptr), data(_data), col(RED){}
};//<T,T&,T*> iterator;//普通迭代器
//<T, const T&, const T*> const_iterator;//指向的东西不能改变:const_iterator,本身不能改变:const iterator
template<class T,class Ref,class Ptr>
struct treeiterator
{typedef RBTtreenode<T> node;typedef treeiterator<T,Ref,Ptr> iterator;node* _node;treeiterator(node* it):_node(it){}Ref operator*(){return _node->data;}Ptr operator->(){return &_node->data;}iterator& operator++(){if (_node->_right){//如果右子树不为空,则找到右子树的最左节点node* cur = _node->_right;while (cur && cur->_left){cur = cur->_left;}_node = cur;}else{//如果右子树为空,且cur是parent的右子树,则先parent回溯至parent->_parent,再_node变为parent//如果右子树为空,且cur是parent的左子树,则_node变为parentnode* cur = _node;node* parent = cur->_parent;while (parent && cur == parent->_right){cur = parent;parent = parent->_parent;}_node = parent;}return *this;}iterator& operator--() //和++反着来即可{if (_node->_left){node* cur = _node->_left;while (cur && cur->_right){cur = cur->_right;}_node = cur;}else{node* cur = _node;node* parent = cur->_parent;while (parent && cur == parent->_left){cur = parent;parent = parent->_parent;}_node = parent;}return *this;}bool operator!=(const iterator&s){return _node != s._node;}
};template<class K, class T,class keyoft>
class RBTtree
{
public:typedef treeiterator<T,T&,T*> iterator;typedef treeiterator<T, const T&, const T*> const_iterator;//指向的东西不能改变typedef RBTtreenode<T> node;iterator begin(){node* flag = root;while (flag&&flag->_left)//flag可能为nullptr{flag = flag->_left;}return iterator(flag);}iterator end(){return iterator(nullptr); //end用nullptr去构造!!!!!!!!}const_iterator begin() const{node* flag = root;while (flag && flag->_left)//flag可能为nullptr{flag = flag->_left;}return const_iterator(flag);}const_iterator end() const{return const_iterator(nullptr); //end用nullptr去构造!!!!!!!!}pair<node*, bool> insert(const T& _data)//!!!!!!!!!{if (root == nullptr){root = new node(_data);root->col = BLACK;//规定根必须是黑的return make_pair(root, true);}node* parent = nullptr; //比bst多了一个parentnode* cur = root;keyoft type;//取出data的K类型的数据while (cur){parent = cur;if (type(cur->data) < type(_data)) //这里取出key再进行比较{cur = cur->_right;}else if (type(cur->data) > type(_data)){cur = cur->_left;}else{return make_pair(cur,false);}}cur = new node(_data);cur->col = RED;//因为如果插入黑色的会使很多节点的一条路径上的黑色节点增多(相当于得罪了所有人),而插入红色则有可能只得罪父亲(如果父亲是红色的话)if (type(parent->data) < type(_data)){parent->_right = cur;}else{parent->_left = cur;}cur->_parent = parent;node* newnode = cur;//开始调整while (parent && parent->col == RED)//parent为黑不需要调整,如果cur变成root,parent就不存在退出循环{node* grandparent = parent->_parent;//祖父一定存在,因为只有根节点是没有祖父的,而根节点一定是黑色的if (parent == grandparent->_left){// g// p unode* uncle = grandparent->_right; //父亲在左则叔叔在右if (uncle && uncle->col == RED) //情况一.如果叔叔存在且为红色{//变色parent->col = uncle->col = BLACK;grandparent->col = RED;//重置cur,parent,继续向上处理cur = grandparent;//变为祖父parent = cur->_parent;}else //叔叔不存在或为黑色,旋转加变色{// g// p// cif (cur == parent->_left) //情况二.单旋{rotateR(grandparent);parent->col = BLACK;grandparent->col = RED;}// g// p// celse //情况三.cur==parent->_right,双旋{rotateL(parent);//经历一次左旋后变成情况二!!!!!!!!!!!(cur和parent换位置)rotateR(grandparent);cur->col = BLACK;grandparent->col = RED;}break;//调整一次就结束了,所以经历过旋转后不需要重置cur,parent,grandparent}}else{// g// u p//node* uncle = grandparent->_left; //父亲在右则叔叔在左if (uncle && uncle->col == RED){parent->col = uncle->col = BLACK;grandparent->col = RED;//cur = grandparent;parent = cur->_parent;}else{// g// u p// cif (cur == parent->_right){rotateL(grandparent);parent->col = BLACK;grandparent->col = RED;}else{// g// u p// crotateR(parent);rotateL(grandparent);cur->col = BLACK;grandparent->col = RED;}break;//调整一次就结束了,所以经历过旋转后不需要重置cur,parent,grandparent}}}//1.如果parent和uncle都为RED,则可以一起变黑// 2.parent为黑不处理// 3.uncle为黑或不存在,parent为红,旋转+变色root->col = BLACK;//最后以防万一让根变为黑return make_pair(newnode, true);}void rotateL(node* parent)//左旋,(新节点插入到较高右子树的右侧)// 1.右右{node* subr = parent->_right;node* subrl = subr->_left;parent->_right = subrl;subr->_left = parent;node* ppnode = parent->_parent;parent->_parent = subr;if (subrl) //subrl可能为空!!!!!!!{subrl->_parent = parent;}if (parent == root) //即如果parent->_parent==nullptr{root = subr;subr->_parent = nullptr;}else{if (ppnode->_left == parent){ppnode->_left = subr;}else if (ppnode->_right == parent){ppnode->_right = subr;}subr->_parent = ppnode;}}void rotateR(node* parent)//右旋,(新节点插入到较高左子树的左侧)// 2.左左{node* subl = parent->_left;node* sublr = subl->_right;parent->_left = sublr;if (sublr) //sublr可能为空!!!!!!!sublr->_parent = parent;node* ppnode = parent->_parent;subl->_right = parent;parent->_parent = subl;if (root == parent){root = subl;subl->_parent = nullptr;}else{if (ppnode->_left == parent){ppnode->_left = subl;}else if (ppnode->_right == parent){ppnode->_right = subl;}subl->_parent = ppnode;}}void inorder(){_inorder(root);}void _inorder(node* root){keyoft type;if (root == nullptr)return;_inorder(root->_left);cout << type(root->data)<< " ";_inorder(root->_right);}bool check(node* it, int blacknum, int flag){if (it == nullptr){if (blacknum == flag)return true;elsereturn false;}else if (it->col == RED && it->_parent->col == RED)//十分巧妙,因为孩子的情况有很多,但父亲不是红就是黑,所以判断父亲更合适return false;else if (it->col == BLACK)blacknum++;return check(it->_left, blacknum, flag) && check(it->_right, blacknum, flag);}bool isbalance(){return _isbalance(root);}bool _isbalance(node* root){if (root == nullptr)return true;else if (root->col == RED)return false;int blacknum = 0;int flag = 0;node* k = root;while (k){if (k->col == BLACK)flag++;k = k->_left;//这里十分巧妙,因为如果为红黑树,从某一节点到空的所有路径上的黑节点数量是一致的,所以可以先随便选一条路径,算出这一条路径上的黑节点数作为基准值,在由递归去和其他路径比较}return check(root, blacknum, flag);}private:node* root = nullptr;
};
myset.h
#include"rbt.h"
namespace zone
{template<class K>class set{public:struct setkeyoft //仿函数,用来取出红黑树节点data中的key{const K& operator()(const K& key){return key;}};//set这里的迭代器本质都是const_iterator,因为k要求无法修改typedef typename RBTtree<K, K, setkeyoft>::const_iterator iterator;//记得要使用typename告诉编译器RBTtree<K, K, setkeyoft>::iterator这个是类型,不是函数typedef typename RBTtree<K, K, setkeyoft>::const_iterator const_iterator;iterator begin()const{return it.begin();}iterator end()const{return it.end();}pair<iterator,bool> insert(const K& key){return it.insert(key);}void inorder(){it.inorder();}private:RBTtree<K,K,setkeyoft> it;};
}
mymap.h
#include"rbt.h"
namespace zone
{template<class K,class T>class map{public:struct setkeyoft{const K& operator()(const pair<K, T>& key){return key.first;}};//map这里的迭代器则使用的是iterator,因为k要求无法修改,但v可以修改,所以可以直接初始化时用pair<const K, T>typedef typename RBTtree<K, pair<const K, T>, setkeyoft>::iterator iterator;typedef typename RBTtree<K, pair<const K, T>, setkeyoft>::const_iterator const_iterator;pair<iterator, bool> insert(const pair<K, T>& key){return it.insert(key);}T& operator[](const K& key){pair<iterator, bool>ret = insert(make_pair(key,T()));//insert返回一个pair,first是iterator,second是bool类型return ret.first->second;}iterator begin(){return it.begin();}iterator end(){return it.end();}void inorder(){it.inorder();}private:RBTtree<K,pair<const K,T>, setkeyoft> it;};
}
test.cpp
#include<iostream>
#include<vector>
#include<string>using namespace std;#include"myset.h"
#include"mymap.h"void test1()
{zone::set<int> it;it.insert(1);it.insert(3);it.insert(5);it.insert(2);it.insert(4);zone::set<int>::iterator arr = it.begin();while (arr!=it.end() ){cout << *arr << " ";++arr;}//it.inorder();}void test2()
{zone::map<string,string> it;it.insert(make_pair("sort","排序"));it.insert(make_pair("right", "右"));it.insert(make_pair("left", "左"));it.insert(make_pair("middle", "中"));zone::map<string,string>::iterator arr = it.begin();while (arr != it.end()){arr->second += 'x';//map的v可修改cout << arr->first << " ";++arr;}//it.inorder();}void test3()
{string arr[] = { "香蕉","苹果","西瓜","苹果","苹果","西瓜","苹果"};zone::map<string, int> it;for (auto e : arr){it[e]++;}for (auto k : it){++k.second;cout << k.first << ":" << k.second << endl;}
}
int main()
{test3();return 0;
}