Reverse Level Order Traversal of Binary Tree

Display a binary tree element in reverse level order. This reverse sequence in from of the bottom to top and left to right in a sequence of binary tree.

Reverse Level Order Traversal of Tree

We can solve this problem in a two different approach.

Method 1: In this process we are use recursion to print tree elements. The logic is first find the deepest node of tree means find the height of tree. After that according to height we are know about how many level are nodes in exist in this tree.

And write a recursive algorithm to print given height level of tree node (left to right). After printing specific level tree nodes thire height of tree are decrement by one, and repeat this process until height of tree is not zero.

In this process we are need to print specific level are required O(n) time and this process are repeat (h) time. h is height of tree. So Overall time complexity of this process are O(n*h).

Method 2: In this method use one stack and one queue, and traversal tree node element by level by level using queue. When perform dequeue() operation in this time add the queue binary tree element into the stack. This process are repeted until queue is not null.

And print all stack elements, In this process are required O(n) time. And space are required O (n) to hold the reference of binary tree nodes.

Here given code implementation process.

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