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.
Example:
Input: [1,2,3,null,5,null,4] Output: [1, 3, 4] Explanation: 1 <--- / \ 2 3 <--- \ \ 5 4 <---
class Solution {
public List<Integer> rightSideView(TreeNode root) {
List<Integer> ans = new ArrayList<>();
robot(root, ans, 0);
return ans;
}
private void robot(TreeNode root, List<Integer> ans, int level) {
if (root == null) {
return;
}
if (ans.size() <= level) {
ans.add(root.val);
}
ans.set(level, root.val);
robot(root.left, ans, level + 1);
robot(root.right, ans, level + 1);
}
}