AdventOfCode-2018/day2.cr

require "./common.cr"

lines = File.read("day2_input").split("\n")
lines.pop

CHARS = ('a'..'z').to_a

def has_n?(string, n)
  return string.chars.count_each(CHARS).any?(&.[](1).==(n))
end

def count_changes(s1, s2)
  pairs = s1.chars.zip s2.chars
  total = 0
  pairs.each do |pair|
    total += 1 if pair[0] != pair[1]
  end
  return total
end

two = lines.count { |s| has_n?(s, 2) }
three = lines.count { |s| has_n?(s, 3) }
puts "\"Hash\": #{two * three}"

lines.product(lines).each do |pair|
  if count_changes(pair[0], pair[1]) == 1
    puts "Strings: #{pair[0]}, #{pair[1]}" 
    exit
  end
end