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算法导论 红黑树 学习 删除(四)
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学习算法 还是建议看看算法导论
算法导论第三版 如果不看数学推导 仅看伪代码 难度还是适中
本系列只是记录我的学习心得 和伪代码转化代码的过程
深入学习 还是建议大家看看算法书籍 教程更加系统。
本文参考算法导论第13章节 红黑树
代码由本人写成
转载请标明出处
先看看不做颜色处理的删除
不做颜色处理的删除基本就和二叉树类似
如果删除节点没有子树 最简单 直接删除
如果待删除的节点只有一个儿子(左子树或者右子树) 那么删除该节点 儿子补上即可
[cpp] view plain copy
- void RBTransplant(std::shared_ptr<node>& root,
- std::shared_ptr<node> u, std::shared_ptr<node> v) {
- if (u->parent_ == nil)
- root = v;
- else if (u == u->parent_->left_)
- u->parent_->left_ = v;
- else
- u->parent_->right_ = v;
- v->parent_ = u->parent_;
- }
u是要删除的节点 v是补上的节点
过程如图:
若是待删除节点有两个子树 那么寻找待删除节点右子树最小的节点,这个节点要么就是删除节点右子树,要么就是沿着删除节点右子树向左遍历的终点
如图: 如果7是待删除节点,那么目标不是11 就是9
将删除节点和目标节点值互换 在处理目标节点 那么就把两棵子树节点的删除更改为无子树或者单子树节点的删除,很巧妙!
伪代码如图
删除代码及测试代码如下(删除未调整颜色版本,可运行)
[cpp] view plain copy
- // rbTreeTest.cpp : 定义控制台应用程序的入口点。
- //
- #include "stdafx.h"
- #include <memory>
- #include <iostream>
- using namespace std;
- enum Color {
- red = 1,
- black
- };
- struct node {
- Color color_;
- std::shared_ptr<node> left_;
- std::shared_ptr<node> right_;
- std::shared_ptr<node> parent_;
- int value_;
- node() {
- left_ = right_ = parent_ = nullptr;
- value_ = -1;
- color_ = black;
- }
- };
- std::shared_ptr<node> nil(new node);
- std::shared_ptr<node> CreateNode(Color color, int i) {
- std::shared_ptr<node> p(new node);
- p->color_ = color;
- p->left_ = nil;
- p->right_ = nil;
- p->parent_ = nil;
- p->value_ = i;
- return p;
- }
- void RightRotate(std::shared_ptr<node>& root, std::shared_ptr<node> x) {
- std::shared_ptr<node> y = x->left_;
- x->left_ = y->right_;
- if (y->right_ != nil)
- y->right_->parent_ = x;
- y->parent_ = x->parent_;
- if (x->parent_ == nil) {
- root = y;
- }
- else if (x->parent_->left_ == x) {
- x->parent_->left_ = y;
- }
- else {
- x->parent_->right_ = y;
- }
- y->right_ = x;
- x->parent_ = y;
- }
- void LeftRotate(std::shared_ptr<node>& root, std::shared_ptr<node> x) {
- std::shared_ptr<node> y = x->right_;
- x->right_ = y->left_;
- if (y->left_ != nil)
- y->left_->parent_ = x;
- y->parent_ = x->parent_;
- if (x->parent_ == nil) {
- root = y;
- }
- else if (x->parent_->left_ == x) {
- x->parent_->left_ = y;
- }
- else {
- x->parent_->right_ = y;
- }
- y->left_ = x;
- x->parent_ = y;
- }
- void PrinTree(std::shared_ptr<node> root) {
- if (root == nil) {
- std::cout << "nil:" << ":color-" << root->color_ << " ; " << std::endl << std::endl;
- return;
- }
- std::cout << root->value_ << ":color-" << root->color_ << "; address:" << root << std::endl;
- if (root->parent_ == nil) {
- std::cout << "parent_:" << "nil" << std::endl;
- }
- else {
- std::cout << "parent_:" << root->parent_->value_ << std::endl;
- }
- if (root->left_ == nil) {
- std::cout << "left_:" << "nil" << std::endl;
- }
- else {
- std::cout << "left_:" << root->left_->value_ << std::endl;
- }
- if (root->right_ == nil) {
- std::cout << "right_:" << "nil" << std::endl;
- }
- else {
- std::cout << "right_:" << root->right_->value_ << std::endl;
- }
- std::cout << std::endl;
- if (root->left_ != nil)
- PrinTree(root->left_);
- if (root->right_ != nil)
- PrinTree(root->right_);
- }
- void RBInsertFixup(std::shared_ptr<node>& root, std::shared_ptr<node> z) {
- while (z->parent_->color_ == red) { //插入节点Z是红色 若Z父节点也是红色则需要调整
- if (z->parent_ == z->parent_->parent_->left_) { // 父节点是左子树的情况
- std::shared_ptr<node> y = z->parent_->parent_->right_;
- if (y->color_ == red) { // 情况1
- z->parent_->color_ = black;
- y->color_ = black;
- z->parent_->parent_->color_ = red;
- z = z->parent_->parent_;
- }
- else {
- if (z == z->parent_->right_) {
- z = z->parent_; // 情况2
- LeftRotate(root, z);
- }
- z->parent_->color_ = black; // 情况3
- z->parent_->parent_->color_ = red;
- RightRotate(root, z->parent_->parent_);
- }
- }
- else {// 父节点是右子树的情况 与上面判断处理均是镜像对称
- std::shared_ptr<node> y = z->parent_->parent_->left_;
- if (y->color_ == red) {
- z->parent_->color_ = black;
- y->color_ = black;
- z->parent_->parent_->color_ = red;
- z = z->parent_->parent_;
- }
- else {
- if (z == z->parent_->left_) {
- z = z->parent_;
- RightRotate(root, z);
- }
- z->parent_->color_ = black;
- z->parent_->parent_->color_ = red;
- LeftRotate(root, z->parent_->parent_);
- }
- }
- }//while (z->parent_->color_ == red)
- root->color_ = black;
- }//function end
- void RBInsert(std::shared_ptr<node>& root, std::shared_ptr<node> ins) {
- std::shared_ptr<node> y = nil;
- std::shared_ptr<node> x = root;
- while (x != nil) {
- y = x;
- if (ins->value_ < x->value_) {
- x = x->left_;
- }
- else {
- x = x->right_;
- }
- }
- ins->parent_ = y;
- if (y == nil) {
- root = ins;
- }
- else if (ins->value_ < y->value_) {
- y->left_ = ins;
- }
- else {
- y->right_ = ins;
- }
- ins->left_ = ins->right_ = nil;
- ins->color_ = red;
- // todo fixup
- RBInsertFixup(root, ins);
- }
- std::shared_ptr<node> CreateRB() {
- std::shared_ptr<node> root = nil;
- std::shared_ptr<node> x = CreateNode(red, 7);
- RBInsert(root, x);
- x = CreateNode(red, 4);
- RBInsert(root, x);
- x = CreateNode(red, 11);
- RBInsert(root, x);
- x = CreateNode(red, 3);
- RBInsert(root, x);
- //PrinTree(root);
- //std::cout << std::endl;
- return root;
- }
- //=============================================
- // delete test
- std::shared_ptr<node> RBMinimum(std::shared_ptr<node> n) {
- while (n->left_ != nil) {
- n = n->left_;
- }
- return n;
- }
- std::shared_ptr<node> RBMaximum(std::shared_ptr<node> n) {
- while (n->right_ != nil) {
- n = n->right_;
- }
- return n;
- }
- std::shared_ptr<node> RBSuccessor(std::shared_ptr<node> n) {
- if (n->right_ != nil)
- return RBMinimum(n->right_);
- std::shared_ptr<node> y = n->parent_;
- while (y != nil && n == y->right_) {
- n = y;
- y = y->parent_;
- }
- return y;
- }
- void RBTransplant(std::shared_ptr<node>& root,
- std::shared_ptr<node> u, std::shared_ptr<node> v) {
- if (u->parent_ == nil)
- root = v;
- else if (u == u->parent_->left_)
- u->parent_->left_ = v;
- else
- u->parent_->right_ = v;
- v->parent_ = u->parent_;
- }
- void RBDelete(std::shared_ptr<node>& root,std::shared_ptr<node> z) {
- if (root == nil || z == nil) {
- return;
- }
- std::shared_ptr<node> y = z;
- Color original_color = y->color_;
- std::shared_ptr<node> x;
- if (z->left_ == nil) {
- x = z->right_;
- RBTransplant(root, z, z->right_);
- }
- else if (z->right_ == nil) {
- x = z->left_;
- RBTransplant(root, z, z->left_);
- }
- else {
- y = RBMinimum(z->right_);
- original_color = y->color_;
- x = y->right_;
- if (y->parent_ == z)
- x->parent_ = y;
- else {
- RBTransplant(root,y,y->right_);
- y->right_ = z->right_;
- y->right_->parent_ = y;
- }
- RBTransplant(root,z,y);
- y->left_ = z->left_;
- y->left_->parent_ = y;
- y->color_ = z->color_;
- }
- if (y->color_ == black) {}
- //RBDeleteFixup(root,x);
- }
- //=============================================
- int main()
- {
- std::shared_ptr<node> root = CreateRB();
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root,root);
- PrinTree(root);
- std::cout << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << std::endl;
- return 0;
- }
最后全部代码如下 增删 打印 调整功能 可运行调试
运行效果
[cpp] view plain copy
- // rbTreeTest.cpp : 定义控制台应用程序的入口点。
- //
- #include "stdafx.h"
- #include <memory>
- #include <iostream>
- using namespace std;
- enum Color {
- red = 1,
- black
- };
- struct node {
- Color color_;
- std::shared_ptr<node> left_;
- std::shared_ptr<node> right_;
- std::shared_ptr<node> parent_;
- int value_;
- node() {
- left_ = right_ = parent_ = nullptr;
- value_ = -1;
- color_ = black;
- }
- };
- std::shared_ptr<node> nil(new node);
- std::shared_ptr<node> CreateNode(Color color, int i) {
- std::shared_ptr<node> p(new node);
- p->color_ = color;
- p->left_ = nil;
- p->right_ = nil;
- p->parent_ = nil;
- p->value_ = i;
- return p;
- }
- void RightRotate(std::shared_ptr<node>& root, std::shared_ptr<node> x) {
- std::shared_ptr<node> y = x->left_;
- x->left_ = y->right_;
- if (y->right_ != nil)
- y->right_->parent_ = x;
- y->parent_ = x->parent_;
- if (x->parent_ == nil) {
- root = y;
- }
- else if (x->parent_->left_ == x) {
- x->parent_->left_ = y;
- }
- else {
- x->parent_->right_ = y;
- }
- y->right_ = x;
- x->parent_ = y;
- }
- void LeftRotate(std::shared_ptr<node>& root, std::shared_ptr<node> x) {
- std::shared_ptr<node> y = x->right_;
- x->right_ = y->left_;
- if (y->left_ != nil)
- y->left_->parent_ = x;
- y->parent_ = x->parent_;
- if (x->parent_ == nil) {
- root = y;
- }
- else if (x->parent_->left_ == x) {
- x->parent_->left_ = y;
- }
- else {
- x->parent_->right_ = y;
- }
- y->left_ = x;
- x->parent_ = y;
- }
- void PrinTree(std::shared_ptr<node> root) {
- if (root == nil) {
- std::cout << "nil:" << ":color-" << root->color_ << " ; " << std::endl << std::endl;
- return;
- }
- std::cout << root->value_ << ":color-" << root->color_ << "; address:" << root << std::endl;
- if (root->parent_ == nil) {
- std::cout << "parent_:" << "nil" << std::endl;
- }
- else {
- std::cout << "parent_:" << root->parent_->value_ << std::endl;
- }
- if (root->left_ == nil) {
- std::cout << "left_:" << "nil" << std::endl;
- }
- else {
- std::cout << "left_:" << root->left_->value_ << std::endl;
- }
- if (root->right_ == nil) {
- std::cout << "right_:" << "nil" << std::endl;
- }
- else {
- std::cout << "right_:" << root->right_->value_ << std::endl;
- }
- std::cout << std::endl;
- if (root->left_ != nil)
- PrinTree(root->left_);
- if (root->right_ != nil)
- PrinTree(root->right_);
- }
- void RBInsertFixup(std::shared_ptr<node>& root, std::shared_ptr<node> z) {
- while (z->parent_->color_ == red) { //插入节点Z是红色 若Z父节点也是红色则需要调整
- if (z->parent_ == z->parent_->parent_->left_) { // 父节点是左子树的情况
- std::shared_ptr<node> y = z->parent_->parent_->right_;
- if (y->color_ == red) { // 情况1
- z->parent_->color_ = black;
- y->color_ = black;
- z->parent_->parent_->color_ = red;
- z = z->parent_->parent_;
- }
- else {
- if (z == z->parent_->right_) {
- z = z->parent_; // 情况2
- LeftRotate(root, z);
- }
- z->parent_->color_ = black; // 情况3
- z->parent_->parent_->color_ = red;
- RightRotate(root, z->parent_->parent_);
- }
- }
- else {// 父节点是右子树的情况 与上面判断处理均是镜像对称
- std::shared_ptr<node> y = z->parent_->parent_->left_;
- if (y->color_ == red) {
- z->parent_->color_ = black;
- y->color_ = black;
- z->parent_->parent_->color_ = red;
- z = z->parent_->parent_;
- }
- else {
- if (z == z->parent_->left_) {
- z = z->parent_;
- RightRotate(root, z);
- }
- z->parent_->color_ = black;
- z->parent_->parent_->color_ = red;
- LeftRotate(root, z->parent_->parent_);
- }
- }
- }//while (z->parent_->color_ == red)
- root->color_ = black;
- }//function end
- void RBInsert(std::shared_ptr<node>& root, std::shared_ptr<node> ins) {
- std::shared_ptr<node> y = nil;
- std::shared_ptr<node> x = root;
- while (x != nil) {
- y = x;
- if (ins->value_ < x->value_) {
- x = x->left_;
- }
- else {
- x = x->right_;
- }
- }
- ins->parent_ = y;
- if (y == nil) {
- root = ins;
- }
- else if (ins->value_ < y->value_) {
- y->left_ = ins;
- }
- else {
- y->right_ = ins;
- }
- ins->left_ = ins->right_ = nil;
- ins->color_ = red;
- // todo fixup
- RBInsertFixup(root, ins);
- }
- std::shared_ptr<node> CreateRB() {
- std::shared_ptr<node> root = nil;
- std::shared_ptr<node> x = CreateNode(red, 15);
- RBInsert(root, x);
- x = CreateNode(red, 10);
- RBInsert(root, x);
- x = CreateNode(red, 20);
- RBInsert(root, x);
- x = CreateNode(red, 5);
- RBInsert(root, x);
- x = CreateNode(red, 13);
- RBInsert(root, x);
- x = CreateNode(red, 17);
- RBInsert(root, x);
- x = CreateNode(red, 25);
- RBInsert(root, x);
- return root;
- }
- //=============================================
- // delete test
- std::shared_ptr<node> RBMinimum(std::shared_ptr<node> n) {
- while (n->left_ != nil) {
- n = n->left_;
- }
- return n;
- }
- std::shared_ptr<node> RBMaximum(std::shared_ptr<node> n) {
- while (n->right_ != nil) {
- n = n->right_;
- }
- return n;
- }
- std::shared_ptr<node> RBSuccessor(std::shared_ptr<node> n) {
- if (n->right_ != nil)
- return RBMinimum(n->right_);
- std::shared_ptr<node> y = n->parent_;
- while (y != nil && n == y->right_) {
- n = y;
- y = y->parent_;
- }
- return y;
- }
- void RBTransplant(std::shared_ptr<node>& root,
- std::shared_ptr<node> u, std::shared_ptr<node> v) {
- if (u->parent_ == nil)
- root = v;
- else if (u == u->parent_->left_)
- u->parent_->left_ = v;
- else
- u->parent_->right_ = v;
- v->parent_ = u->parent_;
- }
- void RBDeleteFixup(std::shared_ptr<node>& root, std::shared_ptr<node> x) {
- while (x != root && x->color_ == black) {
- if (x == x->parent_->left_) {
- std::shared_ptr<node> w = x->parent_->right_;
- if (w->color_ == red) {
- w->color_ = black;
- x->parent_->color_ = red;
- LeftRotate(root, x->parent_);
- w = x->parent_->right_;
- }
- if (w->left_->color_ == black && w->right_->color_ == black) {
- w->color_ = red;
- x = x->parent_;
- }
- else {
- if (w->right_->color_ == black) {
- w->left_->color_ = black;
- w->color_ = red;
- RightRotate(root,w);
- w = x->parent_->right_;
- }
- w->color_ = x->parent_->color_;
- x->parent_->color_ = black;
- w->right_->color_ = black;
- LeftRotate(root,x->parent_);
- x = root;
- }
- }else {
- std::shared_ptr<node> w = x->parent_->left_;
- if (w->color_ == red) {
- w->color_ = black;
- x->parent_->color_ = red;
- RightRotate(root, x->parent_);
- w = x->parent_->left_;
- }
- if (w->right_->color_ == black && w->left_->color_ == black) {
- w->color_ = red;
- x = x->parent_;
- }
- else {
- if (w->left_->color_ == black) {
- w->right_->color_ = black;
- w->color_ = red;
- LeftRotate(root, w);
- w = x->parent_->left_;
- }
- w->color_ = x->parent_->color_;
- x->parent_->color_ = black;
- w->left_->color_ = black;
- RightRotate(root, x->parent_);
- x = root;
- }
- }
- }//while (x != root && x->color_ == black)
- x->color_ = black;
- }
- void RBDelete(std::shared_ptr<node>& root,std::shared_ptr<node> z) {
- if (root == nil || z == nil)
- return;
- std::shared_ptr<node> y;
- std::shared_ptr<node> x;
- if (z->left_ == nil || z->right_ == nil) {
- y = z;
- }
- else {
- y = RBSuccessor(z);
- }
- if (y->left_ != nil) {
- x = y->left_;
- }
- else {
- x = y->right_;
- }
- x->parent_ = y->parent_;
- if (y->parent_ == nil) {
- root = x;
- }
- else {
- if (y == y->parent_->left_) {
- y->parent_->left_ = x;
- }
- else {
- y->parent_->right_ = x;
- }
- }
- if (y != z) {
- z->value_ = y->value_;
- }
- if (y->color_ == black) {
- //todo
- RBDeleteFixup(root,x);
- }
- }
- //=============================================
- int main()
- {
- std::shared_ptr<node> root = CreateRB();
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root,root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- RBDelete(root, root);
- PrinTree(root);
- std::cout << "===========================" << std::endl;
- return 0;
- }
算法导论 红黑树 学习 删除(四)
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