Leetcode-symmetric Tree

with regard to the related operation of the mirror tree, recursion can be used to solve the problem easily.

Be careful to determine if the root node is null

/** * Definition for Binary tree * public class TreeNode {*     int val, *     TreeNode left, *     TreeNode right; *
  
   treenode (int x) {val = x;} *} */public class Solution {public    Boolean issymmetric (TreeNode root) {if (root = = nul L) {return true;} return Dfs (Root.left, root.right); Public boolean DFS (TreeNode-left, TreeNode-right) {if (left==null && right==null) {return true;} if (Left!=nul L&&right==null) | | (left==null&&right!=null) | | Left.val!=right.val) {return false;} return Dfs (Left.left, right.right) && dfs (left.right, right.left); }}
  

Leetcode-symmetric Tree