Print the nodes at odd levels of a tree

The above code prints nodes in preorder way. If we wish to print nodes level by level, we can use level order traversal. The idea is based on Print level order traversal line by line
We traverse nodes level by level. We switch odd level flag after every level.

Print the nodes at odd levels of a tree : https://www.geeksforgeeks.org/print-nodes-odd-levels-tree/