Codeforces Round #340 Div2

cf340-div2-a-Elephant.rb

n = gets.chomp.to_i
a = n / 5
b = n % 5
if b == 0 then
  puts a
else
  puts a + 1
end

cf340-div2-b-Chocolate.rb

n = gets.chomp.to_i
a = gets.chomp.split(" ").map(&:to_i)
nut = []
a.each_with_index do |i, j|
  if i == 1 then
    nut << j
  end
end
dnut = []
(1..(nut.length - 1)).each do |i|
  dnut << nut[i] - nut[i - 1]
end
if a.all?{|v| v == 0} then
  puts 0
elsif dnut.empty? then
  puts 1
else
  puts dnut.inject(:*)
end

cf340-div2-c-WateringFlowers.rb

n, x1, y1, x2, y2 = gets.chomp.split(" ").map(&:to_i)
dist = []

n.times do
  fx, fy = gets.chomp.split(" ").map(&:to_i)
  d1 = (x1 - fx)**2 + (y1 - fy)**2
  d2 = (x2 - fx)**2 + (y2 - fy)**2
  dist << [d1, d2]
end
dist << [0,0]

res = Float::INFINITY
dist.each do |i|
  r1 = i[0]
  r2 = 0
  dist.each do |j|
    if j[0] > r1 then
      r2 = [r2, j[1]].max
    end
  end
  res = [res, r1 + r2].min
end

puts res