判断二叉树是否对称
import java.util.*;
/*
* public class TreeNode {
* int val = 0;
* TreeNode left = null;
* TreeNode right = null;
* }
*/
public class Solution {
/**
*
* @param root TreeNode类
* @return bool布尔型
*/
public boolean robot(TreeNode left,TreeNode right){
if(left==null && right==null){
return true;
}else{
if(left==null || right==null){
return false;
}
}
return left.val==right.val && robot(left.left,right.right) && robot(left.right,right.left);
}
public boolean isSymmetric(TreeNode root) {
if(root==null){
return true;
}
return robot(root.left,root.right);
}
}