Symmetric Treethis
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).code
For example, this binary tree [1,2,2,3,4,4,3] is symmetric:ip
1 / \ 2 2 / \ / \ 3 4 4 3
But the following [1,2,2,null,3,null,3] is not:leetcode
1 / \ 2 2 \ \ 3 3
Note: Bonus points if you could solve it both recursively and iteratively.get
class Solution { public boolean isSymmetric(TreeNode root) { if(root==null) return true; else{ return sysmmetric(root.left, root.right); } } public boolean sysmmetric(TreeNode left, TreeNode right){ if(left==null || right == null){ return left==right; } if(left.val != right.val){ return false; } return sysmmetric(left.left, right.right) && sysmmetric(left.right, right.left); } }