133. Reverse Level Order Traversal of Binary Trees

Objective: - Given a binary tree, Do the reverse level order traversal. In our earlier post, we have seen normal Level Order Traversal. In reverse level order traversal we first need to print the last level followed by the second last level up to the root, which is the first level.

Example:

 Approach: Use Stack

• Use the Queue and do the level order traversal, read "Level Order Traversal" First if you don't know the technique.
• Instead of printing the Node, keep adding it to Stack.
• At the End print all the nodes from Stack, it will be in reverse order than normal level order traversal.

7 6 5 4 3 2 1