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101. Symmetric binary tree

️ Give you the root node of a binary tree root , Check whether it is axisymmetric

️ 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

️ Tips ：

• The number of nodes in the tree is in the range [1, 1000] Inside

• -100 <= Node.val <= 100

class Solution {
    
    public boolean isSymmetric(TreeNode root) {
    
  if(root==null){
    
      return true;
  }
  return isMirror(root,root);
    }
      boolean isMirror(TreeNode r1,TreeNode r2){
    
       if(r1==null&&r2==null){
    
           return true;
       }
       if(r1==null||r2==null){
    
           return false;
       }
       return (r1.val==r2.val)&&isMirror(r1.left,r2.right)&&isMirror(r1.right,r2.left);

  }
}