LeetCode-Binary Tree Right Side View

Posted 2020-08-08 LiBlog

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].

Credits:
Special thanks to @amrsaqr for adding this problem and creating all test cases.

Solution:

/**
 * 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> resList = new LinkedList<Integer>();
        rightSideViewRecur(root,resList,1);
        return resList;
    }
    
    public void rightSideViewRecur(TreeNode curNode, List<Integer> resList, int depth){
        if (curNode==null){
            return;
        }
        
        if (resList.size()<depth){
            resList.add(curNode.val);
        }
        
        rightSideViewRecur(curNode.right,resList,depth+1);
        rightSideViewRecur(curNode.left,resList,depth+1);
    }
}