Grokking Graph Algorithms for Coding Interviews
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All Nodes Distance K in Binary Tree (medium)
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Problem Statement

Given the root of a binary tree, a target node, and a distance k, find all the nodes in the tree that are exactly k edges away from the target node. You may return these nodes' values in any order.

Examples

Example 1

  • Input: root = [1, 2, 3, 4, 5, null, 6, 7, 8], target = 3, k = 1
Image
  • Expected Output: [6, 1]
  • Justification: Nodes 1 and 6 are one edge away from node 3.

Example 2

  • Input: root = [1, 2, 3, null, 4, 5, 6], tarrget = 2, k = 2
Image
  • Expected Output: [3]
  • Justification: Node 3 is two edges away from node 2.

Example 3

  • Input: root = [1, 2, 3, 4, 5, null, null, null, null, 6, 7], target = 4, k = 3
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  • Expected Output: [6, 7, 3]
  • Justification: Nodes 6, 7 and 3 are three edges away from node 4.

Constraints:

  • The number of nodes in the tree is in the range [1, 500].
  • 0 <= Node.val <= 500
  • All the values Node.val are unique.
  • target is the value of one of the nodes in the tree.
  • 0 <= k <= 1000

Try it yourself

Try solving this question here:

Python3
Python3
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