algorithms/src/test/java/tree/AVLTree.java at master · verifyCode/algorithms · GitHub

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package tree;

import com.tree.Tree;

import java.util.LinkedList;

import java.util.Optional;

import java.util.Queue;

import java.util.Stack;

/**

* @author xjn

* @since 2020-05-07

public class AVLTree<E extends Comparable<E>> implements Tree<E> {

private class Node {

public E e;

public Node left;

public Node right;

public int height;

public Node(E e) {

this.e = e;

this.left = this.right = null;

this.height = 1;

}

public Node(Node node) {

this.e = node.e;

this.left = node.left;

this.right = node.right;

this.height = node.height;

}

@Override

public String toString() {

return e.toString();

}

private Node root;

private int size;

public AVLTree() {

this.root = null;

this.size = 0;

}

private int getHeight(Node node) {

if (node == null) {

return 0;

}

return node.height;

}

private int getBalanceFactor(Node node) {

if (node == null) {

return 0;

}

return getHeight(node.left) - getHeight(node.right);

}

public boolean isAVL() {

return isAVL(this.root);

}

private boolean isAVL(Node node) {

if (node == null) {

return true;

}

int leftHeight = getHeight(node.left);

int rightHeight = getHeight(node.right);

if (Math.abs(leftHeight - rightHeight) > 1) {

return false;

}

return isAVL(node.left) && isAVL(node.right);

}

@Override

public boolean isEmpty() {

return size == 0;

}

@Override

public int getSize() {

return this.size;

}

@Override

public void add(E e) {

}

private Node addRecursive(Node node, E e) {

if (node == null) {

node = new Node(e);

size++;

return node;

}

if (node.e.compareTo(e) < 0) {

node.left = addRecursive(node.left, e);

} else if (node.e.compareTo(e) > 0) {

node.right = addRecursive(node.right, e);

}

//更新height

node.height = 1 + Math.max(getHeight(node.left), getHeight(node.right));

//平衡因子

int balanceFactory = getBalanceFactor(node);

//RR

if (balanceFactory > 1 && getBalanceFactor(node.left) >= 0) {

return rotateRight(node);

}

//LL

if (balanceFactory < -1 && getBalanceFactor(node.right) <= 0) {

return rotateLeft(node);

}

//LR

if (balanceFactory > 1 && getBalanceFactor(node.left) < 0) {

node.left = rotateLeft(node.left);

return rotateRight(node);

}

//RL

if (balanceFactory < -1 && getBalanceFactor(node.right) > 0) {

node.right = rotateRight(node.right);

return rotateLeft(node);

}

return node;

}

private Node rotateRight(Node y) {

Node x = y.left;

Node t3 = x.right;

x.right = y;

y.left = t3;

y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;

x.height = Math.max(getHeight(x.right), getHeight(x.left)) + 1;

return x;

}

private Node rotateLeft(Node y) {

Node x = y.right;

Node t3 = x.left;

x.left = y;

y.right = t3;

y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;

x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;

return x;

}

@Override

public boolean contains(E e) {

return false;

}

private boolean containsRecursive(Node node, E e) {

if (node == null) {

return false;

}

if (node.e.compareTo(e) == 0) {

return true;

} else if (node.e.compareTo(e) > 0) {

return containsRecursive(node.left, e);

} else {

return containsRecursive(node.right, e);

}

@Override

public void preOrder() {

preOrder(root);

}

private void preOrder(Node node) {

if (node == null) {

return;

}

System.out.print(node);

preOrder(node.left);

preOrder(node.right);

}

@Override

public void inOrder() {

inOrder(root);

}

private void inOrder(Node node) {

if (node == null) {

return;

}

preOrder(node.left);

System.out.print(node);

preOrder(node.right);

}

@Override

public void postOrder() {

postOrder(root);

}

private void postOrder(Node node) {

if (node == null) {

return;

}

postOrder(node.left);

postOrder(node.right);

System.out.print(node);

}

@Override

public void bfs() {

Queue<Node> queue = new LinkedList<>();

queue.add(root);

while (!queue.isEmpty()) {

Node node = queue.remove();

System.out.print(node + " ");

if (node.left != null) {

queue.add(node.left);

}

if (node.right != null) {

queue.add(node.right);

}

@Override

public void dfs() {

Stack<Node> stack = new Stack<>();

stack.push(root);

while (!stack.isEmpty()) {

Node nodeFromStack = stack.pop();

System.out.print(nodeFromStack.e + " ");

if (nodeFromStack.right != null) {

stack.push(nodeFromStack.right);

}

if (nodeFromStack.left != null) {

stack.push(nodeFromStack.left);

}

@Override

public int getTreeDepth() {

return getTreeDepth(root);

}

private int getTreeDepth(Node node) {

if (node == null) {

return 0;

}

int left = getTreeDepth(node.left) + 1;

int right = getTreeDepth(node.right) + 1;

return Math.max(left, right);

}

@Override

public E maximum() {

return maximum(root).e;

}

private Node maximum(Node node) {

if (node == null || node.left == null) {

return node;

}

return maximum(node.left);

}

@Override

public E minimum() {

return minimum(root).e;

}

private Node minimum(Node node) {

if (node == null || node.right == null) {

return node;

}

return minimum(node.right);

}

@Override

public E removeMaximum() {

E e = maximum();

root = removeMaximum(root);

return e;

}

private Node removeMaximum(Node node) {

if (node.left == null) {

size--;

return node.right;

}

node.left = removeMaximum(node.left);

return node;

}

@Override

public E removeMinimum() {

return null;

}

private Node removeMinimum(Node node) {

if (node.right == null) {

size--;

return node.left;

}

node.right = removeMinimum(node.right);

return node;

}

@Override

public void remove(E e) {

}

private Node remove(Node node, E e) {

if (node == null) {

return null;

}

Node retNode = null;

if (node.e.compareTo(e) < 0) {

node.left = remove(node.left, e);

retNode = node;

} else if (node.e.compareTo(e) > 0) {

node.right = remove(node.right, e);

retNode = node;

}

//找到删除的位置 node

//左子树为空

if (node.left == null) {

Node rightNode = node.right;

node.right = null;

size--;

retNode = rightNode;

} else if (node.right == null) {

//右子树为空

Node leftNode = node.left;

node.left = null;

size--;

retNode = leftNode;

} else {

//左右子树不为空

Node successor = minimum(node.right);

successor.left = node.left;

successor.right = removeMinimum(node.right);

node.left = node.right = null;

retNode = successor;

}

if (retNode == null) {

return null;

}

//更新height

retNode.height = Math.max(getHeight(retNode.right), getHeight(retNode.left)) + 1;

//计算平衡因子

int balanceFactor = getBalanceFactor(retNode);

//右旋

if (balanceFactor > 1 && getBalanceFactor(retNode.left) >= 0) {

return rotateRight(retNode);

}

//左旋

if (balanceFactor < -1 && getBalanceFactor(retNode.right) <= 0) {

return rotateLeft(retNode);

}

//LR

if (balanceFactor > 1 && getBalanceFactor(retNode.left) < 0) {

retNode.left = rotateLeft(retNode.left);

return rotateRight(retNode);

}

//RL

if (balanceFactor < -1 && getBalanceFactor(retNode.right) > 0) {

retNode.right = rotateRight(retNode.right);

return rotateLeft(retNode);

}

return retNode;

}

private void writeArray(Node node, int rowIndex, int columnIndex, String[][] res, int treeDepth) {

//输入的树不为空

if (node == null) {

return;

}

//当前节点保存到二维数组中

res[rowIndex][columnIndex] = String.valueOf(node.e);

//当前节点位于树的第几层

int currLevel = (rowIndex + 1) / 2;

//如果到了最后一行,则返回

if (currLevel == treeDepth) {

return;

}

// 计算当前行到下一行，每个元素之间的间隔（下一行的列索引与当前元素的列索引之间的间隔）

int gap = treeDepth - currLevel - 1;

// 对左儿子进行判断，若有左儿子，则记录相应的"/"与左儿子的值

if (node.left != null) {

res[rowIndex + 1][columnIndex - gap] = "/";

writeArray(node.left, rowIndex + 2, columnIndex - gap * 2, res, treeDepth);

}

// 对右儿子进行判断，若有右儿子，则记录相应的"\"与右儿子的值

if (node.right != null) {

res[rowIndex + 1][columnIndex + gap] = "\\";

writeArray(node.right, rowIndex + 2, columnIndex + gap * 2, res, treeDepth);

}

private String show(Node node) {

StringBuilder builder = new StringBuilder();

if (root == null) {

return "EMPTY!";

}

int treeDepth = getTreeDepth();

// 最后一行的宽度为2的（n - 1）次方乘3，再加1

// 作为整个二维数组的宽度

int arrayHeight = treeDepth * 2 - 1;

int arrayWidth = (2 << (treeDepth - 2)) * 3 + 1;

// 用一个字符串数组来存储每个位置应显示的元素

String[][] res = new String[arrayHeight][arrayWidth];

// 对数组进行初始化，默认为一个空格

for (int i = 0; i < arrayHeight; i++) {

for (int j = 0; j < arrayWidth; j++) {

res[i][j] = " ";

}

// 从根节点开始，递归处理整个树

// res[0][(arrayWidth + 1)/ 2] = (char)(root.val + '0');

writeArray(node, 0, arrayWidth / 2, res, treeDepth);

// 此时，已经将所有需要显示的元素储存到了二维数组中，将其拼接并打印即可

for (String[] line : res) {

StringBuilder sb = new StringBuilder();

for (int i = 0; i < line.length; i++) {

sb.append(line[i]);

if (line[i].length() > 1 && i <= line.length - 1) {

i += line[i].length() > 4 ? 2 : line[i].length() - 1;

}

builder.append(sb.toString() + "\n");

}

return builder.toString();

}

algorithms/src/test/java/tree/AVLTree.java at master · verifyCode/algorithms · GitHub

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