Tree top view problm

#1

am not able to understand sample test case
please help

https://hack.codingblocks.com/contests/c/511/953

#2

Hey Jai, given input for tree is 1 2 3 4 5 6 -1 -1 -1 -1 -1 -1 -1 which will result in a tree like this.

     1      
    /  \     
   /    \    
  2      3       
 / \      \   
/   \      \  
4   5       6

now if you view this tree from top you will see the nodes 4 2 1 3 and that’s the answer. So, basically you have to print the nodes from left to right which can be seen if we view the tree from the top.