题解 | 对称的二叉树

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pRoot TreeNode类 
     * @return bool布尔型
     */
    public boolean isSymmetrical (TreeNode pRoot) {
        // write code here
        if(pRoot == null){
            return true;
        }
        Queue<TreeNode> q1 = new LinkedList();
        Queue<TreeNode>q2 = new LinkedList();
        q1.offer(pRoot.left);
        q2.offer(pRoot.right);
        while(!q1.isEmpty()&&!q2.isEmpty()){
            TreeNode left = q1.poll();
            TreeNode right = q2.poll();
            if(left == null&&right == null){
                continue;
            }
            if(left == null||right == null||left.val!=right.val){
                return false;
            }
            q1.offer(left.left);
            q1.offer(left.right);
            q2.offer(right.right);
            q2.offer(right.left);
        }
    
        return true;
    }
}

使用队列来分别存储左右也是很好的思路