#863

All Nodes Distance K in Binary Tree

medium · verified · 67.5% accepted · 12,075 likes · top 74%

hash table · tree · depth-first search · breadth-first search · binary tree

⊣ practice⊣ open on leetcode ↗

Description

Given the root of a binary tree, the value of a target node target, and an integer k, return an array of the values of all nodes that have a distance k from the target node.

You can return the answer in any order.

Example 1:

Input: root = [3,5,1,6,2,0,8,null,null,7,4], target = 5, k = 2
Output: [7,4,1]
Explanation: The nodes that are a distance 2 from the target node (with value 5) have values 7, 4, and 1.

Example 2:

Input: root = [1], target = 1, k = 3
Output: []

Solution