Codeforces #339 Div2

cf339-a-Link-Cut-Tree.rb

l, r, k = gets.chomp.split(" ").map(&:to_i)

from = Math.log(l, k)
to = Math.log(r, k)

a = ((from.floor)..(to.ceil)).to_a.map{|i| k**i}.keep_if{|i| i >= l and i <= r}
if a.length == 0 then
  puts -1
else
  puts a.join(" ")
end

cf339-div2-b- Genas-Code.rb

n = gets.chomp.split(" ").map(&:to_i)
tanks = gets.chomp.split(" ")

pow = 0
notbeautiful = "1"
tanks.each do |t|
  n1 = t.count("1")
  n0 = t.count("0")
  nrem = t.length - n1 - n0
  if t.length == 1 && n0 == 1 then
    puts 0
    exit
  elsif n1 != 1 or nrem != 0 then
    notbeautiful = t
  else
    pow += t.length - 1
  end
end
puts notbeautiful + "0" * pow