LeetCode has become a cornerstone for coding interview preparation, offering a plethora of challenges that span across algorithmic concepts and programming languages. While languages like Python and Java often dominate the discussion around solving LeetCode problems, Ruby offers its unique set of advantages due to its expressive syntax and powerful standard library. In this article, we delve into how Ruby can be an excellent choice for tackling LeetCode challenges, supported by Ruby code examples that demonstrate its capabilities.

Why Ruby for LeetCode?

Ruby’s concise syntax and rich collection of built-in methods allow for rapid prototyping and problem-solving, making it a potent tool for LeetCode challenges. Its readability and elegance not only make solutions easy to understand but also reduce the likelihood of bugs. Moreover, Ruby’s dynamic nature and powerful enumeration methods can simplify complex algorithms, allowing developers to focus on the logic rather than language-specific boilerplate.

Ruby Features Beneficial for LeetCode

  • Enumerable Module: Ruby’s Enumerable module provides a comprehensive set of methods for traversing, searching, sorting, and manipulating collections. These methods can significantly reduce the complexity of data handling in coding challenges.
  • First-Class Functions: Ruby treats functions as first-class citizens, making it easy to pass functions as arguments, return them from other functions, or assign them to variables. This feature is particularly useful for callbacks and higher-order functions.
  • Simplicity and Expressiveness: Ruby’s syntax is designed to be intuitive and close to natural language, which can help in quickly translating thought processes into working code.

Example Problems Solved in Ruby

Let’s walk through a couple of LeetCode problems and solve them using Ruby, showcasing its expressiveness and efficiency.

Example 1: Two Sum (LeetCode Problem #1)

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

def two_sum(nums, target)
  hash_map = {}
  nums.each_with_index do |num, index|
    complement = target - num
    return [hash_map[complement], index] if hash_map[complement]
    hash_map[num] = index

puts two_sum([2, 7, 11, 15], 9).inspect  # Output: [0, 1]

This solution utilizes a hash map to store and quickly retrieve the complement values, demonstrating Ruby’s efficient data handling and ease of implementing complex algorithms.

Example 2: Valid Parentheses (LeetCode Problem #20)

Given a string s containing just the characters '(', ')', '{', '}', '[', and ']', determine if the input string is valid. An input string is valid if:

  • Open brackets must be closed by the same type of brackets.
  • Open brackets must be closed in the correct order.
def is_valid(s)
  stack = []
  mapping = { ')' => '(', '}' => '{', ']' => '[' }
  s.chars.each do |char|
    if mapping[char]
      top_element = stack.empty? ? '#' : stack.pop
      return false unless mapping[char] == top_element

puts is_valid("()[]{}")  # Output: true
puts is_valid("(]")      # Output: false

This Ruby code uses a stack to track opening brackets and maps closing brackets to their respective openers, efficiently verifying the string’s validity.


Ruby’s elegance, combined with its powerful programming constructs, makes it an exceptional choice for solving LeetCode challenges. Its syntax is not only clean and readable but also expressive enough to implement solutions to complex problems succinctly. By utilizing Ruby’s features to their fullest, developers can enhance their problem-solving skills and prepare for coding interviews effectively. Let Ruby’s charm guide you through your LeetCode journey, and you might find yourself not only succeeding in your coding challenges but also enjoying the process along the way.