题解 | #判断是不是完全二叉树#

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 root TreeNode类 
     * @return bool布尔型
     */
    public boolean isCompleteTree (TreeNode root) {
        // write code here
        Queue<TreeNode> que=new LinkedList<>();
        que.offer(root);
        while(!que.isEmpty()){
            TreeNode cur=que.poll();
            if(cur==null){
                while(!que.isEmpty()){
                    cur=que.poll();
                    if(cur!=null)return false;
                }
                break;
            }
            que.offer(cur.left);
            que.offer(cur.right);
        }
        return true;
    }
}