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Permutations in Ruby Programming: Generating All Possible Combinations in Ruby

   January 30, 2024
Ruby @ Freshers.in

Permutations are a fundamental concept in mathematics and computer science. They represent all possible arrangements of elements in a set. In this article, we’ll explore how to implement a function in Ruby to generate all possible permutations of a given array of elements. Understanding permutations and being able to generate all possible combinations of elements in an array is a valuable skill in programming. In this article, we will explore how to implement a Ruby function to achieve this.

Understanding Permutations

A permutation of a set is an arrangement of its elements in a specific order. For example, given the set {1, 2, 3}, its permutations include {1, 2, 3}, {1, 3, 2}, {2, 1, 3}, {2, 3, 1}, {3, 1, 2}, and {3, 2, 1}.

The Ruby Function

Let’s start by defining a Ruby function called generate_permutations to generate all possible permutations of an input array.

def generate_permutations(arr)
  return [arr] if arr.length <= 1
  permutations = []
  arr.each_with_index do |element, index|
    rest = arr[0...index] + arr[(index + 1)..-1]
    generate_permutations(rest).each do |perm|
      permutations << [element] + perm
    end
  end

  return permutations
end

Example Usage

Now, let’s explore some examples to see how our generate_permutations function works:

input_array_1 = [1, 2, 3]
permutations_1 = generate_permutations(input_array_1)

puts "Input Array: #{input_array_1}"
puts "Permutations:"
permutations_1.each do |perm|
  puts perm.inspect
end

Output:

Input Array: [1, 2, 3]
Permutations:
[1, 2, 3]
[1, 3, 2]
[2, 1, 3]
[2, 3, 1]
[3, 1, 2]
[3, 2, 1]

In this example, we successfully generated all possible permutations of the input array [1, 2, 3].

Another Example:

input_array_2 = ['A', 'B', 'C']
permutations_2 = generate_permutations(input_array_2)

puts "Input Array: #{input_array_2}"
puts "Permutations:"
permutations_2.each do |perm|
  puts perm.inspect
end

Output:

Input Array: ["A", "B", "C"]
Permutations:
["A", "B", "C"]
["A", "C", "B"]
["B", "A", "C"]
["B", "C", "A"]
["C", "A", "B"]
["C", "B", "A"]

Here, we’ve successfully generated all possible permutations of the input array ['A', 'B', 'C'].

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