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feat(codes/cpp/chapter_tree/avl_tree.cpp): create 'avl_tree.cpp'

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mgisr 2022-12-03 17:15:51 +08:00
parent 1d9a076cdd
commit e9996b37d6
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codes/cpp/chapter_tree/avl_tree.cpp Normal file
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/*
* File: avl_tree.cpp
* Created Time: 2022-12-2
* Author: mgisr (maguagua0706@gmail.com)
*/
#include "../include/include.hpp"
class AvlTree {
private:
TreeNode *root{};
static bool isBalance(const TreeNode *p);
static int getBalanceFactor(const TreeNode *p);
static void updateHeight(TreeNode *p);
void fixBalance(TreeNode *p);
static bool isLeftChild(const TreeNode *p);
static TreeNode *&fromParentTo(TreeNode *node);
public:
AvlTree() = default;
AvlTree(const AvlTree &p) = default;
const TreeNode *search(int val);
bool insert(int val);
bool remove(int val);
void printTree();
};
// 判断该结点是否平衡
bool AvlTree::isBalance(const TreeNode *p) {
int balance_factor = getBalanceFactor(p);
if (-1 <= balance_factor && balance_factor <= 1) { return true; }
else { return false; }
}
// 获取当前结点的平衡因子
int AvlTree::getBalanceFactor(const TreeNode *p) {
if (p->left == nullptr && p->right == nullptr) { return 0; }
else if (p->left == nullptr) { return (-p->right->height); }
else if (p->right == nullptr) { return p->left->height; }
else { return p->left->height - p->right->height; }
}
// 更新结点高度
void AvlTree::updateHeight(TreeNode *p) {
if (p->left == nullptr && p->right == nullptr) { p->height = 1; }
else if (p->left == nullptr) { p->height = p->right->height + 1; }
else if (p->right == nullptr) { p->height = p->left->height + 1; }
else { p->height = std::max(p->left->height, p->right->height) + 1; }
}
void AvlTree::fixBalance(TreeNode *p) {
// 左旋操作
auto rotate_left = [&](TreeNode *node) -> TreeNode * {
TreeNode *temp = node->right;
temp->parent = p->parent;
node->right = temp->left;
if (temp->left != nullptr) {
temp->left->parent = node;
}
temp->left = node;
node->parent = temp;
updateHeight(node);
updateHeight(temp);
return temp;
};
// 右旋操作
auto rotate_right = [&](TreeNode *node) -> TreeNode * {
TreeNode *temp = node->left;
temp->parent = p->parent;
node->left = temp->right;
if (temp->right != nullptr) {
temp->right->parent = node;
}
temp->right = node;
node->parent = temp;
updateHeight(node);
updateHeight(temp);
return temp;
};
// 根据规则选取旋转方式
if (getBalanceFactor(p) > 1) {
if (getBalanceFactor(p->left) > 0) {
if (p->parent == nullptr) { root = rotate_right(p); }
else { fromParentTo(p) = rotate_right(p); }
} else {
p->left = rotate_left(p->left);
if (p->parent == nullptr) { root = rotate_right(p); }
else { fromParentTo(p) = rotate_right(p); }
}
} else {
if (getBalanceFactor(p->right) < 0) {
if (p->parent == nullptr) { root = rotate_left(p); }
else { fromParentTo(p) = rotate_left(p); }
} else {
p->right = rotate_right(p->right);
if (p->parent == nullptr) { root = rotate_left(p); }
else { fromParentTo(p) = rotate_left(p); }
}
}
}
// 判断当前结点是否为其父节点的左孩子
bool AvlTree::isLeftChild(const TreeNode *p) {
if (p->parent == nullptr) { return false; }
return (p->parent->left == p);
}
// 返回父节点指向当前结点指针的引用
TreeNode *&AvlTree::fromParentTo(TreeNode *node) {
if (isLeftChild(node)) { return node->parent->left; }
else { return node->parent->right; }
}
const TreeNode *AvlTree::search(int val) {
TreeNode *p = root;
while (p != nullptr) {
if (p->val == val) { return p; }
else if (p->val > val) { p = p->left; }
else { p = p->right; }
}
return nullptr;
}
bool AvlTree::insert(int val) {
TreeNode *p = root;
if (p == nullptr) {
root = new TreeNode(val);
return true;
}
for (;;) {
if (p->val == val) { return false; }
else if (p->val > val) {
if (p->left == nullptr) {
p->left = new TreeNode(val, p);
break;
} else {
p = p->left;
}
} else {
if (p->right == nullptr) {
p->right = new TreeNode(val, p);
break;
} else {
p = p->right;
}
}
}
for (; p != nullptr; p = p->parent) {
if (!isBalance(p)) {
fixBalance(p);
break;
} else { updateHeight(p); }
}
return true;
}
bool AvlTree::remove(int val) {
TreeNode *p = root;
if (p == nullptr) { return false; }
while (p != nullptr) {
if (p->val == val) {
TreeNode *real_delete_node = p;
TreeNode *next_node;
if (p->left == nullptr) {
next_node = p->right;
if (p->parent == nullptr) { root = next_node; }
else { fromParentTo(p) = next_node; }
} else if (p->right == nullptr) {
next_node = p->left;
if (p->parent == nullptr) { root = next_node; }
else { fromParentTo(p) = next_node; }
} else {
while (real_delete_node->left != nullptr) {
real_delete_node = real_delete_node->left;
}
std::swap(p->val, real_delete_node->val);
next_node = real_delete_node->right;
if (real_delete_node->parent == p) { p->right = next_node; }
else { real_delete_node->parent->left = next_node; }
}
if (next_node != nullptr) {
next_node->parent = real_delete_node->parent;
}
for (p = real_delete_node; p != nullptr; p = p->parent) {
if (!isBalance(p)) { fixBalance(p); }
updateHeight(p);
}
delete real_delete_node;
return true;
} else if (p->val > val) {
p = p->left;
} else {
p = p->right;
}
}
return false;
}
void inOrder(const TreeNode *root) {
if (root == nullptr) return;
inOrder(root->left);
cout << root->val << ' ';
inOrder(root->right);
}
void AvlTree::printTree() {
inOrder(root);
cout << endl;
}
int main() {
AvlTree tree = AvlTree();
// tree.insert(13);
// tree.insert(24);
// tree.insert(37);
// tree.insert(90);
// tree.insert(53);
tree.insert(53);
tree.insert(90);
tree.insert(37);
tree.insert(24);
tree.insert(13);
tree.remove(90);
tree.printTree();
const TreeNode *p = tree.search(37);
cout << p->val;
return 0;
}