All Nodes Distance K in Binary Tree

Given a binary tree (each node has a unique value), a target node, and an integer K, return a list of the values of all nodes that have a distance K from the target node target. Note: The list returned can be in any order. Example Input: root = [3,5,1,6,2,0,8,null,null,7,4] target = 5 K = 2 Output: [7,4,1] Constraints The tree is non-empty. The distance K from the target is defined as the number of different nodes from target to the node. The number of nodes in the tree is less than 500. Every node has a unique value. Example Input [3,5,1,6,2,0,8,null,null,7,4] 5 2