91 lines
2.3 KiB
Java
91 lines
2.3 KiB
Java
/*
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* File: TreeNode.java
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* Created Time: 2022-11-25
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* Author: Krahets (krahets@163.com)
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*/
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package include;
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import java.util.*;
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/**
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* Definition for a binary tree node.
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*/
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public class TreeNode {
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public int val; // 结点值
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public int height; // 结点高度
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public TreeNode left; // 左子结点引用
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public TreeNode right; // 右子结点引用
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public TreeNode(int x) {
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val = x;
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}
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/**
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* Generate a binary tree with an array
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* @param arr
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* @return
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*/
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public static TreeNode arrToTree(Integer[] arr) {
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if (arr.length == 0)
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return null;
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TreeNode root = new TreeNode(arr[0]);
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Queue<TreeNode> queue = new LinkedList<>() {{ add(root); }};
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int i = 1;
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while(!queue.isEmpty()) {
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TreeNode node = queue.poll();
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if(arr[i] != null) {
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node.left = new TreeNode(arr[i]);
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queue.add(node.left);
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}
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i++;
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if(arr[i] != null) {
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node.right = new TreeNode(arr[i]);
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queue.add(node.right);
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}
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i++;
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}
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return root;
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}
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/**
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* Serialize a binary tree to a list
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* @param root
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* @return
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*/
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public static List<Integer> treeToList(TreeNode root) {
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List<Integer> list = new ArrayList<>();
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if(root == null) return list;
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Queue<TreeNode> queue = new LinkedList<>() {{ add(root); }};
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while(!queue.isEmpty()) {
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TreeNode node = queue.poll();
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if(node != null) {
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list.add(node.val);
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queue.add(node.left);
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queue.add(node.right);
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}
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else {
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list.add(null);
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}
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}
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return list;
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}
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/**
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* Get a tree node with specific value in a binary tree
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* @param root
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* @param val
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* @return
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*/
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public static TreeNode getTreeNode(TreeNode root, int val) {
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if (root == null)
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return null;
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if (root.val == val)
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return root;
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TreeNode left = getTreeNode(root.left, val);
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TreeNode right = getTreeNode(root.right, val);
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return left != null ? left : right;
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}
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}
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