Symmetric Tree

采用递归的方式

public class Solution {public static void main(String[] args) {// TODO Auto-generated method stub}public boolean isSymmetric(TreeNode root) {        if(root == null)        return true;        return judgeSym(root.left,root.right);                    }public boolean judgeSym(TreeNode left,TreeNode right){if(left==null&&right==null)return true;if(left==null||right==null)return false;if(left.val == right.val){return judgeSym(left.left, right.right)&&judgeSym(left.right, right.left);//只有两边都为真的时候才是真}elsereturn false;}}class TreeNode {    int val;    TreeNode left;    TreeNode right;    TreeNode(int x)    {    val = x;    }}