input = DATA.readlines(chomp: true)
  .flat_map.with_index {|row, y|
    row.chars.map.with_index {|chr, x|
      [[y,x], chr]
    }
  }.to_h

# part one
dirs = (-1..1).flat_map {|dy| (-1..1).map {|dx| [dy,dx] }}
dirs.delete([0,0])
dirs = dirs.map {|dy, dx|
  4.times.map {|i| [dy*i, dx*i] }
}

pp input.keys.sum {|y, x|
  dirs.count {|deltas|
    deltas.map {|dy, dx| input[[y+dy, x+dx]] }.join == "XMAS"
  }
}

# part two
diagonals = [
  [[-1, 1], [1, -1]],
  [[-1, -1], [1, 1]],
]
pp input.keys.select {|y, x|
  input[[y,x]] == ?A && diagonals.all? {|deltas|
    deltas.map {|dy,dx| input[[y+dy, x+dx]] }.to_set == Set["M", "S"]
  }
}.size

__END__
MMMSXXMASM
MSAMXMSMSA
AMXSXMAAMM
MSAMASMSMX
XMASAMXAMM
XXAMMXXAMA
SMSMSASXSS
SAXAMASAAA
MAMMMXMMMM
MXMXAXMASX