题目：
Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
For example:
Given the following binary tree,
1 <---
/ 2 3 <---
\ 5 4 <---
You should return [1, 3, 4].
题意及分析：给出一棵二叉树，求每一层最右节点组成的序列。宽度遍历，取出每一层的最后一个点即可。
代码：
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public List<Integer> rightSideView(TreeNode root) { List<Integer> res = new ArrayList<>(); if(root==null) return res; Queue<TreeNode> queue = new LinkedList<>(); Queue<TreeNode> tempQueue = new LinkedList<>(); queue.add(root); while(!queue.isEmpty()||!tempQueue.isEmpty()){ if(!queue.isEmpty()){ TreeNode node = queue.poll(); if(node.left!=null){ tempQueue.add(node.left); } if(node.right!=null){ tempQueue.add(node.right); } if(queue.isEmpty()) //最后一个点 res.add(node.val); }else{ queue = new LinkedList<>(tempQueue); tempQueue.clear(); } } return res; } }
[LeetCode] 199. Binary Tree Right Side View Java
原文：http://www.cnblogs.com/271934Liao/p/7230854.html