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
Constraints:
[1, 1000].-100 <= Node.val <= 100
class Solution {
public boolean helper(TreeNode root1 , TreeNode root2){
if(root1 == null || root2 == null){
return root1 == root2 ;
}
if(root1.val == root2.val){
boolean ans1 = helper(root1.left , root2.right);
boolean ans2 = helper(root1.right,root2.left);
return ans1 && ans2 ;
}else{
return false ;
}
}
public boolean isSymmetric(TreeNode root) {
if(root==null){
return true ;
}
return helper(root.left , root.right);
}
}
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