Leetcode 993 : 二叉树的堂兄弟节点

最新推荐文章于 2024-05-29 23:06:21 发布

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该博客提供了一个Java实现的算法，用于解决LeetCode上的问题：判断二叉树中两个节点是否为堂兄弟节点。算法通过广度优先搜索遍历二叉树，并在遍历过程中记录节点的深度和父节点信息，从而确定两个节点是否在同一层但有不同的父节点。

https://leetcode-cn.com/problems/cousins-in-binary-tree/

考察点：二叉树遍历、二叉树节点深度记录、二叉树当前节点父节点记录

import java.util.LinkedList;
import java.util.Queue;

public class BinaryTreeIsBrother {


    public static class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }

    public static boolean isCousins(TreeNode root, int x, int y) {
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            boolean xFlag = false;
            TreeNode xRoot = null;
            boolean yFlag = false;
            TreeNode yRoot = null;
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                if (node.left != null) {
                    queue.offer(node.left);
                    if (node.left.val == x) {
                        xFlag = true;
                        xRoot = node;
                    }
                    if (node.left.val == y) {
                        yFlag = true;
                        yRoot = node;
                    }
                }
                if (node.right != null) {
                    queue.offer(node.right);
                    if (node.right.val == x) {
                        xFlag = true;
                        xRoot = node;
                    }
                    if (node.right.val == y) {
                        yFlag = true;
                        yRoot = node;
                    }
                }
                if (xFlag && yFlag && (xRoot.val != yRoot.val)) {
                    return true;
                }
            }
        }
        return false;
    }

    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(3);
        root.left.left = new TreeNode(4);
        root.left.right = new TreeNode(5);
        root.right.left = new TreeNode(6);
        root.right.right = new TreeNode(7);
        System.out.println(isCousins(root, 5, 6));
    }


}