Binary Tree Right Side View

https://leetcode.com/problems/binary-tree-right-side-view/

Given A binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can SE E ordered from top to bottom.

For example:
Given The following binary tree,

   1            <---/   2     3         <---\       5     4       <---

You should return [1, 3, 4] .

Problem Solving Ideas:

This problem is relatively simple, hierarchical traversal, each layer output the last node can be.

/*** Definition for Binary tree * public class TreeNode {* Int. val; * TreeNode left; * TreeNode right; * TreeNode (int x) {val = x;} }*/ Public classSolution { PublicList<integer>Rightsideview (TreeNode root) {List<Integer> result =NewArraylist<integer>(); if(Root = =NULL) {            returnresult; } Queue<TreeNode> queue =NewLinkedlist<treenode>();                Queue.offer (root);  while(Queue.size () > 0) {            intSize =queue.size ();  while(Size > 0) {TreeNode current=Queue.poll (); if(Current.left! =NULL) {queue.offer (current.left); }                if(Current.right! =NULL) {queue.offer (current.right); }                if(Size = = 1) {result.add (current.val); } size--; }        }        returnresult; }}

Binary Tree Right Side View