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All Nodes Distance K in Binary Tree

MediumP2Coding

Given a binary tree, a target node in it and an integer k, return the values of all nodes that are exactly k edges away from the target. Distance is measured along tree edges and may go up through parents as well as down. Return the values in any order.

The target is given as a value; the harness passes you the node of the tree that holds it. All values in the tree are unique.

Example 1

Input
root = [3,5,1,6,2,0,8,null,null,7,4], target = 5, k = 2
Output
[7,4,1]
Why
7 and 4 are below 5; 1 is reached through the parent 3.

Example 2

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

Constraints

  • 1 <= number of nodes <= 500
  • 0 <= Node.val <= 500
  • Values are unique and target is in the tree.
  • 0 <= k <= 1000

Hints

Run checks the 3 visible tests, Submit all 9.