kayak.rb

def found_sequence?(grid, sequence, position, direction)
  return true if sequence.size == 0
  row,col = position
  return false if [row,col].min < 0
  return false if row >= grid.length
  return false if col >= grid[row].length
  return false if grid[row][col] != sequence[0]
  dy,dx = direction
  return found_sequence?(grid, sequence[1..-1],[row+dy,col+dx],direction)
end

def find_sequence(grid,sequence)
  # Define some directions, just to make the code simpler
  directions = {
    east: [0, 1],
    south: [1, 0],
    south_east: [1, 1],
    south_west: [-1, 1]}

  grid.each_with_index do |row_str,row|
    row_str.chars.each_with_index do |col_char,col|
      directions.each do |dir, vector|
        if found_sequence?(grid,sequence,[row,col],vector)
          puts "Found #{sequence} at row #{row}, col #{col}, direction: #{dir}"
        end
      end
    end
  end
end

# Create an array of rows
grid =
"AAYKAKAYKAYYKKAAKAYAAAYKYKYAYK
KYYAKYAAAYKAAKKYAKKKAAAKAAYKAA
KKKYAKAKAYKKYKKYKKAKYAAAAKAAKK
YKAAKYAAKKKKKAYAYYYYYAAKAAKKKK
KKAYYAAKKYYAYAAKAAKKAAYKAKKAAK
KKAAAKAAAKKAKKKYAAAYKYAYAKYKAA
KKYKAAAAAAAAAAKKAAAKYYAKAKAKKY
KKKKKKAKYYKYYKKAAYAKAAAKYAKKAA
KAKKAKAYKAAYAKYYKKAYKKKAAAAAKA
KKAKAKAKAAAKAYAYKAKAYYAYKKAKYY
AAAYAKKKAKKAKYKAYKKAKKYKAAKKYY
YKKKYKKYAAAKKKKAKAYKKKKKAAKKKY
KKAKAYKAAKAKKYYAKAYAAKYAAAAAAA
AAAAKKYAAKKAAYKKAAAYAYAKYAKAYK
AKKAKKAYKAAYKYKAKYAAKKYKKKKKKA
KYKAAKKYAYKAKKKYKAKAYAYKYAAAKK
KAYYKKAKYKAYAAKAYAAYYYAKKYKYKK
KKKKAKAYAAAKKAYAYKKYAKAAAAYKAY
AYKAKKKAAKAKAYAAAKKYKKAYKAYAYY
KYAYKAYAKAKYYKYKAKAAYKYKKAYKAK
AKAKKAKKAKKKKAAAKYYYYKAKAAAAAK
KAKYYKAKKYKYAKYAAAAAKAKAYAAKKA
KKAAAKKAKAKKAAKAYAAYAAAKKAAYYA
KAKKYYKKAYAYKKAKKYYKYKYKKAAAKA".split("\n")

sequence = "KAYAK"

find_sequence(grid,sequence)