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].
思路：
层次遍历法。遍历到每层最后一个节点时，把其放到结果集中。
/** * Definition for a binary tree node. * function TreeNode(val) { * this.val = val; * this.left = this.right = null; * } */ /** * @param {TreeNode} root * @return {number[]} */ var rightSideView = function(root) { var res=[]; if(root==null){ return res; } var queue=[]; queue.push(root); while(queue.length!=0){ for(var i=0,len=queue.length;i<len;i++){ var cur=queue.pop(); if(cur.right){ queue.push(cur.right); } if(cur.left){ queue.push(cur.left); } } res.push(cur.val); } return res; };
【树】Binary Tree Right Side View
原文：http://www.cnblogs.com/shytong/p/5184455.html