Binary Tree Right Side View

Problem

Given the root of 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.

Examples

The brute-force approach

BFS level by level. At each level, collect all nodes and take the last one (rightmost).

result = []
queue = [root]
while queue:
    level_size = len(queue)
    for i in range(level_size):
        node = queue.pop(0)
        if i == level_size - 1:
            result.append(node.val)
        if node.left: queue.append(node.left)
        if node.right: queue.append(node.right)
return result

O(n) — this is already optimal. BFS level-order is the natural approach.

Spotting the pattern

This is a Tree Traversal problem. The key question to ask yourself:

After processing all nodes at a level, which one is the "rightmost"? How do you identify it during BFS?

Answering that is where it clicks, and it's exactly what the guided walkthrough below builds with you: the pattern reasoning, a progressive hint ladder that never spoils the answer, a row-by-row dry run, the optimized solution, and an in-browser editor to run your code against real test cases.