Print nodes at k distance from root

Given a root of a tree, and an integer k. Print all the nodes which are at k distance from root. 
For example, in the below tree, 4, 5 & 8 are at distance 2 from root. 
 

           1
         /   \
       2      3
     /  \    /
   4     5  8

Print nodes at k distance from root: https://www.geeksforgeeks.org/print-nodes-at-k-distance-from-root/