Symmetric Tree

 Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).

 

Example 1:

Input: root = [1,2,2,3,4,4,3]
Output: true

Example 2:

Input: root = [1,2,2,null,3,null,3]
Output: false
class Solution {
    public boolean isSymmetric(TreeNode root) {        
        return isMirror(root.left, root.right);        
    }
    
    public boolean isMirror(TreeNode t1, TreeNode t2)
    {
        if(t1==null && t2==null) return true;
        if(t1==null || t2==null) return false;
        
        return t1.val==t2.val  && isMirror(t1.left, t2.right) &&                                 isMirror(t1.right, t2.left);
    }
}


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