Minimum Spanning Tree in Ruby

Minimum Spanning

Tree in Ruby

Welcome to the Minimum Spanning Tree in Ruby page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

# frozen_string_literal: true

USAGE = "Usage: please provide a comma-separated list of integers"

def usage!
  warn USAGE
  exit 1
end

def parse_input
  raw = ARGV.first
  usage! if raw.nil? || raw.strip.empty?

  nums = raw.split(",").map { Integer(it.strip) }
  n = Integer(Math.sqrt(nums.length))
  usage! unless n * n == nums.length

  Array.new(n) { |i| nums[i * n, n] }
rescue ArgumentError, NoMethodError
  usage!
end

def find(parent, x)
  (parent[x] == x) ? x : (parent[x] = find(parent, parent[x]))
end

def union(parent, rank, a, b)
  a = find(parent, a)
  b = find(parent, b)
  return if a == b

  if rank[a] < rank[b]
    parent[a] = b
  elsif rank[a] > rank[b]
    parent[b] = a
  else
    parent[b] = a
    rank[a] += 1
  end
end

def mst_weight(matrix)
  n = matrix.size

  edges =
    (0...n).flat_map do |i|
      (i + 1...n).map do |j|
        w = matrix[i][j]
        w.positive? ? [w, i, j] : nil
      end
    end.compact

  edges.sort_by!(&:first)

  parent = (0...n).to_a
  rank = Array.new(n, 0)

  edges.reduce(0) do |total, (w, u, v)|
    next total if find(parent, u) == find(parent, v)

    union(parent, rank, u, v)
    total + w
  end
end

matrix = parse_input
puts mst_weight(matrix)

Minimum Spanning Tree in Ruby was written by:

• Ștefan-Iulian Alecu

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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How to Run the Solution

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