Print Binary Tree levels in sorted order | Set 2 (Using set)

Given a tree, print the level order traversal in sorted order.

Examples : 

Input : 7
 / \
 6 5
 / \ / \
 4 3 2 1
 
Output : 
7
5 6
1 2 3 4 

Input : 7
 / \
 16 1
 / \ 
 4 13 
 
Output :
7 
1 16
4 13

We have discussed a priority queue based solution in below post.
Print Binary Tree levels in sorted order | Set 1 (Using Priority Queue)

In this post, a set (which is implemented using balanced binary search tree) based solution is discussed.

Approach : 

1. Start level order traversal of tree. 
2. Store all the nodes in a set(or any other similar data structures). 
3. Print elements of set.

Implementation:

7 5 6 1 2 3 4 

Time Complexity: O(n*log(n)) where n is the number of nodes in the binary tree.
Auxiliary Space: O(n) where n is the number of nodes in the binary tree.