minimum_buss.rb

#ruby 2.7.2

# Description:
# Galih and Ratna married during the COVID19 period
# and only invited the families of both parters.
# They rented a number of minibus to pick up all of
# their families to go to wedding. But during the COVID19,
# the government held a PSBB program to reduce the impact
# of the spread of the virus. Each minibus only can carry
# at most 4 passengers.

# What a minimum of busses will they needed to rent
# if all member of each family should ride in the same
# Busses. (One bus can't take more than two family)


# INPUT:
# 1. The first line contains integer n -- the number of families
# 2. The second line contains a sequence of integer.
# The integers arw sparated by space, each integer is
# the number of members in the family.

# OUTPUT:
# 1. Print the single number -- the minimum number of
# of busses nessecery to drive all family to the wedding
# 2. Print "Input must be equal with count of family" if
# number of family isn't equal with count of family

# Test Case
# 1. n = 5, s = 1 2 4 3 3, result = 4
# 2. n = 8, s = 2 3 4 4 2 1 3 1, result = 5
# 3. n = 5, s = 1 5, result = message

require 'rspec'

MAX_PASSENGER = 4

def minimum_bus(number_of_family, family_members)
  members = family_members.split(' ').map(&:to_i)
  return 'Input must be equal with count of family' if members.length != number_of_family

  busses          = 0
  hash_passengers = {}

  members.each do |member|
    next if member > MAX_PASSENGER

    if member == MAX_PASSENGER
      busses += 1
    elsif hash_passengers[member].nil?
      hash_passengers[member] = member
      busses += 1
    elsif (hash_passengers[member] + member) < MAX_PASSENGER
      hash_passengers[member] = nil
    end
  end

  busses
end

RSpec.describe 'Count minimum buss for each families' do
  it 'should be return \'Input must be equal with count of family\' bus for 5 family \'1 5\'' do
    expect(minimum_bus(5, '1 5')).to eq('Input must be equal with count of family')
  end

  it 'should be return 4 bus for 5 family \'1 2 4 3 3\'' do
    expect(minimum_bus(5, '1 2 4 3 3')).to eq(4)
  end

  it 'should be return 5 bus for 8 family \'2 3 4 4 2 1 3 1\'' do
    expect(minimum_bus(8, '2 3 4 4 2 1 3 1')).to eq(5)
  end

  it 'should be return 2 bus for 4 family \'1 1 1 1\'' do
    expect(minimum_bus(4, '1 1 1 1')).to eq(2)
  end

  it 'should be return 3 bus for 6 family \'2 2 1 1 1 1\'' do
    expect(minimum_bus(6, '2 2 1 1 1 1')).to eq(3)
  end

  it 'should be return 7 bus for 11 family \'4 2 2 2 4 1 1 1 1 3 1\'' do
    expect(minimum_bus(11, '4 2 2 2 4 1 1 1 1 3 1')).to eq(7)
  end
end