questions

prob1.rb

def getUserInput
  gets.chomp.split(" ").map(&:to_i)
end

total_stops, vacant_seats = getUserInput
standing_stops = 0
(total_stops-1).downto(1) do |s|
  stop = getUserInput
  vacant_seats += (stop[1] - stop[0])
  standing_stops += 1 if vacant_seats.eql?(0)
end

print standing_stops


prob2.rb

def getUserInput
  gets.chomp.split(" ").map(&:to_i)
end

n, k = getUserInput
a = getUserInput
c = a.combination(2).to_a
print c.collect{|i| i.sort.reverse.inject(:-)}.sort[n-1]

prob3.rb

def getUserInput
  gets.chomp.split(" ").map(&:to_i)
end
size = gets.chomp.to_i
elements = getUserInput
occurances = gets.chomp.to_i
print elements.select{|i| elements.count(i) == occurances}.min