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].
Top view, Bot view, right view, and left view.
1 /** 2 * Definition for binary tree 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 public class Solution { 11 public List<Integer> rightSideView(TreeNode root) { 12 List<Integer> result = new ArrayList<Integer>(); 13 if(root == null) return result; 14 LinkedList<TreeNode> queue = new LinkedList<TreeNode>(); 15 queue.add(root); 16 queue.add(null); 17 int level = 0; 18 while(queue.size() != 1){ 19 TreeNode tmp = queue.poll(); 20 if(tmp == null){ 21 queue.add(null); 22 level ++; 23 }else{ 24 if(result.size() == level){ 25 result.add(tmp.val); 26 }else{ 27 result.set(level,tmp.val); 28 } 29 if(tmp.left != null)queue.add(tmp.left); 30 if(tmp.right != null)queue.add(tmp.right); 31 } 32 } 33 return result; 34 } 35 }