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LeetCode 199: Binary Tree Right Side View

LeetCode Problem #199 — Binary Tree Right Side View Solve LeetCode Binary Tree Right Side View using JavaScript and Binary Search. This solution finds the optimal result using Modified Binary Search in O(n) time.

Problem Information

Property Value
Problem Binary Tree Right Side View
LeetCode #199
Difficulty Medium
Language JavaScript
Algorithm Modified Binary Search
Data Structure Sorted Array
Pattern Binary Search
Time Complexity O(n)
Space Complexity O(1)

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 .

Key Insight

Exploit sorted ordering or monotonic properties to eliminate half of the search space at each step in $O(\log n)$ time.

Approach

We iterate through the input using Depth-First Search (DFS) / Breadth-First Search (BFS). By maintaining state efficiently in a Tree / Graph / Grid, we eliminate redundant operations and process each element in optimal time.

Algorithm

  1. Initialize state variables / data structure (Sorted Array).
  2. Process elements sequentially using Modified Binary Search.
  3. Validate boundary conditions and return optimal result.

Example

Consider the standard input for Binary Tree Right Side View. Applying Modified Binary Search yields the target result step by step.

Complexity

  • Time Complexity: O(n)
  • Space Complexity: O(1)

Pattern

Binary Search

Topics

  • Binary Search
  • Divide and Conquer
  • Search Space

Language

JavaScript

Source Code

Why This Works

By utilizing Binary Search, each element is processed efficiently, ensuring optimal performance while avoiding unnecessary re-computations.

Common Mistakes

  1. Applying standard binary search without accounting for array rotation or duplicates.
  2. Off-by-one errors when updating boundary pointers (left = mid + 1 vs right = mid - 1).
  3. Integer overflow during midpoint calculation (use mid = left + (right - left) // 2).

Interview Notes

  • Tests: Logarithmic search space reduction, boundary handling, and invariant preservation.
  • Follow-up: How does performance change if the array contains duplicate elements?

Related Problems

LeetCode

View problem on LeetCode