java || easiest solution
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n/**\n * Definition for a binary tree node.\n * public class TreeNode {\n *     int val;\n *     TreeNode left;\n *     TreeNode right;\n *     TreeNode() {}\n *     TreeNode(int val) { this.val = val; }\n *     TreeNode(int val, TreeNode left, TreeNode right) {\n *         this.val = val;\n *         this.left = left;\n *         this.right = right;\n *     }\n * }\n */\n\nclass Solution {\n    static boolean mir( TreeNode t1 , TreeNode t2 )\n    {\n        if( t1==null && t2== null ) return true;\n        else if( t1==null || t2==null ) return false;\n\n        return ( t1.val==t2.val ) && mir( t1.right , t2.left ) && mir( t1.left , t2.right );\n    }\n    public boolean isSymmetric(TreeNode root) \n    {\n        return mir( root , root );\n    \n    }\n}\n```
['Java']