Solving Symmetric Tree in Javascript. Please try yourself first to solve the problem and submit your implementation to LeetCode before looking into solution.

Problem Description

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

	    1
	   / \
	  2   2
	 / \ / \
	3  4 4  3

But the following [1,2,2,null,3,null,3] is not:

	    1
	   / \
	  2   2
	   \   \
	   3    3

Note: Bonus points if you could solve it both recursively and iteratively.

See the full details of the problem Symmetric Tree at LeetCode

Originally posted at: @github.com/ignacio-chiazzo/Algorithms-Leetcode-Javascript