今天给红黑树添加几个函数,分别是:
find()查找
findMin()查找最小的
findMax()查找最大的
isEmpty()判断树是不是空的
makeEmpty()清空树
在头文件中添加Except.h、Wrapper.h和RedBlackTree.h在源文件中添加TestRedBlackTree.cpp
下面是异常的定义
//Except.h
#ifndef EXCEPT_H
#define EXCEPT_H
#include<string>
using namespace std;
class DSException{
public:
DSException(const string & msg = "") :message(msg){}
virtual ~DSException(){}
virtual string toString() const{
return "Exception " + string(":") + what();
}
virtual string what() const{
return message;
}
private:
string message;
};
class DuplicateItemException :public DSException{
public:
DuplicateItemException(const string & msg = "") :DSException(msg){}
};
class NullPointerException: public DSException{
public:
NullPointerException(const string & msg = "") :DSException(msg){}
};
#endif
下面是引用的返回类型。
//Wrapper.h
#ifndef WRAPPER_H_
#define WRAPPER_H_
#include "Except.h"
template<class Object>
class Cref{
public:
Cref() :obj(NULL){}
explicit Cref(const Object & x) :obj(&x){}
bool isNull() const{
return obj == NULL;
}
const Object & get() const{
if (isNull()) throw NullPointerException(); else return *obj;
}
private:
const Object *obj;
};
#endif
下面是红黑树主要的程序,我们把红黑树写在头文件里面。
//RedBlackTree.h
//红黑树主程序,包含了红黑树主要的基本的功能
#ifndef RED_BLACK_TREE_H_
#define RED_BLACK_TREE_H_
#include"Except.h"
#include"Wrapper.h"
template<class Comparable>
class RedBlackTree;
template<class Comparable>
class RedBlackNode;
template<class Comparable>
class RedBlackTree{
public:
RedBlackTree(const Comparable & negInf);//红黑树的构造函数
~RedBlackTree();
enum{RED,BLACK};
Cref<Comparable> find(const Comparable & x) const;//返回一个引用类型,但是引用类型不能指着空对象,所以我们自己做一个返回类型。
Cref<Comparable> findMin() const;
Cref<Comparable> findMax() const;
bool isEmpty() const;//用来判断二叉树是不是空树
void makeEmpty();
void insert(const Comparable & x);
typedef RedBlackNode<Comparable> Node;
//private:为了测试,临时变成公有的
public:
Node *header;
Node *nullNode;
Node *current;//当前节点
Node *parent;//父结点
Node *grand;//祖父节点
Node *great;//曾祖父节点
void reclaimMemory(Node *t)const;
void rotateWithLeftChild(Node * & k2) const;
void rotateWithRightChild(Node * & k1) const;
void doubleRotateWithLeftChild(Node * & k3)const;
void doubleRotateWithRightChild(Node * & k4)const;
void handleReorient(const Comparable & item);
RedBlackNode<Comparable>* rotate(const Comparable & item, Node *parent)const;//返回旋转以后的根
};
template<class Comparable>
class RedBlackNode{
//private:为了测试,临时变成public
public:
Comparable element;
RedBlackNode *left;
RedBlackNode *right;
int color;
RedBlackNode(const Comparable & theElement = Comparable(),
RedBlackNode *lt = NULL,
RedBlackNode *rt = NULL,
int c = RedBlackTree<Comparable>::BLACK)
:element(theElement), left(lt), right(rt), color(c){}
friend class RedBlackTree<Comparable>;
};
template<class Comparable>
RedBlackTree<Comparable>::RedBlackTree(const Comparable & negInf){
nullNode = new Node();
nullNode->left = nullNode->right = nullNode;
header = new Node(negInf);
header->left = header->right = nullNode;
}
template<class Comparable>
RedBlackTree<Comparable>::~RedBlackTree(){
makeEmpty();
delete nullNode;
delete header;
}
template<class Comparable>
void RedBlackTree<Comparable>::insert(const Comparable & x){
current = parent = grand = header;
nullNode->element = x;
while (current->element != x){//查找新节点插入的位置
great = grand; grand = parent; parent = current;
current = x < current->element ? current->left : current->right;
if (current->left->color == RED && current->right->color == RED)
handleReorient(x);
}
if (current != nullNode)
throw DuplicateItemException();
current = new Node(x, nullNode, nullNode);
if (x < parent->element)
parent->left = current;
else
parent->right = current;
handleReorient(x);
//自动平衡 -> 红黑树
}
template<class Comparable>
void RedBlackTree<Comparable>::rotateWithLeftChild(Node * & k2)const{
Node *k1 = k2->left;
k2->left = k1->right;//横向移动
k1->right = k2;
k2 = k1;
}
template<class Comparable>
void RedBlackTree<Comparable>::rotateWithRightChild(Node * & k1)const{
Node *k2 = k1->right;
k1->right = k2->left;
k2->left = k1;
k1 = k2;
}
template<class Comparable>//双旋转_向右旋转
void RedBlackTree<Comparable>::doubleRotateWithLeftChild(Node * & k3)const{
rotateWithRightChild(k3->left);
rotateWithLeftChild(k3);
}
template<class Comparable>//双旋转_向左旋转
void RedBlackTree<Comparable>::doubleRotateWithRightChild(Node * & k4)const{
rotateWithLeftChild(k4->right);
rotateWithRightChild(k4);
}
template<class Comparable>
void RedBlackTree<Comparable>::handleReorient(const Comparable & item){
//变色
current->color = RED;
current->left->color = BLACK;
current->right->color = BLACK;
//旋转
if (parent->color == RED){
grand->color = RED;
if (item < grand->element != item < parent->element)//如果是内部孙子,有两次旋转
parent = rotate(item, grand);
current = rotate(item, great);
current->color = BLACK;
}
header->right->color = BLACK;
}
template<class Comparable>
RedBlackNode<Comparable>* RedBlackTree<Comparable>::rotate(const Comparable & item, Node * theParent)const{
if (item < theParent->element){
item < theParent->left->element ? rotateWithLeftChild(theParent->left) : rotateWithRightChild(theParent->left);
return theParent->left;
}
else{
item < theParent->right->element ? rotateWithLeftChild(theParent->right) : rotateWithRightChild(theParent->right);
return theParent->right;
}
}
template<class Comparable>
bool RedBlackTree<Comparable>::isEmpty()const{
return header->right == nullNode;
}
template<class Comparable>
void RedBlackTree<Comparable>::makeEmpty(){
reclaimMemory(header->right);
header->right = nullNode;
}
template<class Comparable>
void RedBlackTree<Comparable>::reclaimMemory(Node *t)const{
if (t != t->left){
reclaimMemory(t->left);
reclaimMemory(t->right);
delete t;
}
}
template<class Comparable>
Cref<Comparable> RedBlackTree<Comparable>::findMin()const{
if (isEmpty())
return Cref<Comparable>();
Node *itr = header->right;
while (itr->left != nullNode)
itr = itr->left;
return Cref<Comparable>(itr->element);
}
template<class Comparable>
Cref<Comparable> RedBlackTree<Comparable>::findMax()const{
if (isEmpty())
return Cref<Comparable>();
Node *itr = header->right;
while (itr->right != nullNode)
itr = itr->right;
return Cref<Comparable>(itr->element);
}
template<class Comparable>
Cref<Comparable> RedBlackTree<Comparable>::find(const Comparable & x)const{
nullNode->element = x;
Node *curr = header->right;
for (;;){
if (x < curr->element)
curr = curr->left;
else if (x>curr->element)
curr = curr->right;
else if (curr != nullNode)
return Cref<Comparable>(curr->element);
else
return Cref<Comparable>();
}
}
#endif
下面的程序是测试红黑树使用的主程序
//TestRedBlackTree.cpp
//测试红黑树
#include<iostream>
#include"RedBlackTree.h"
using namespace std;
int main(){
cout << "测试红黑树:" << endl;
const int NEG_INF = -99999;//负的无穷大,
RedBlackTree<int> t(NEG_INF);//创建一个空树,
t.insert(50);
t.insert(40);
t.insert(30);
t.insert(20);
t.insert(10);
t.insert(5);
t.insert(4);
t.insert(3);
cout << t.header->right->element << endl;
if (!t.isEmpty())cout << "红黑树不是空的" << endl;
t.makeEmpty();
if (t.isEmpty())cout << "红黑树是空的" << endl;
t.insert(200);
t.insert(100);
t.insert(90);
t.insert(50);
t.insert(80);
t.insert(70);
t.insert(60);
if (t.findMin().get() == 50)cout << "找到最小数" << endl;
if (t.findMax().get() == 200)cout << "找到最大值" << endl;
Cref<int> r = t.find(60);
if (r.isNull()){
cout << "没找到!" << endl;
}
else{
cout << "找到:" << r.get() << endl;
}
system("pause");
return 0;
}
总结:今天把红黑树的基本功能都实现出来,代码比较长,但是绝对值得学习,以后的开发过程中也是这样写,一点一点把函数的功能加到我们的树里面。