healingroom.rb

module FlowerPuzzle
  refine Array do
    def to_i
      reduce(0) { |acc, e| acc * 3 + e }
    end

    def apply_move(move)
      zip(move).map { |a, b| (a + b) % 3 }
    end
  end
end

INITIAL_STATE = [
  0, 0, 0, 0,
  0, 2, 2, 0,
  0, 0, 0, 0,
].freeze

MOVES = [
  [
    2, 1, 0, 0,
    1, 0, 0, 0,
    0, 0, 0, 0,
  ],
  [
    1, 2, 1, 0,
    0, 1, 0, 0,
    0, 0, 0, 0,
  ],
  [
    0, 1, 2, 1,
    0, 0, 1, 0,
    0, 0, 0, 0,
  ],
  [
    0, 0, 1, 2,
    0, 0, 0, 1,
    0, 0, 0, 0,
  ],
  [
    1, 0, 0, 0,
    2, 1, 0, 0,
    1, 0, 0, 0,
  ],
  [
    0, 1, 0, 0,
    1, 2, 1, 0,
    0, 1, 0, 0,
  ],
  [
    0, 0, 1, 0,
    0, 1, 2, 1,
    0, 0, 1, 0,
  ],
  [
    0, 0, 0, 1,
    0, 0, 1, 2,
    0, 0, 0, 1,
  ],
  [
    0, 0, 0, 0,
    1, 0, 0, 0,
    2, 1, 0, 0,
  ],
  [
    0, 0, 0, 0,
    0, 1, 0, 0,
    1, 2, 1, 0,
  ],
  [
    0, 0, 0, 0,
    0, 0, 1, 0,
    0, 1, 2, 1,
  ],
  [
    0, 0, 0, 0,
    0, 0, 0, 1,
    0, 0, 1, 2,
  ],
].freeze
MOVES.each(&:freeze)

using FlowerPuzzle

def search(initial_state)
  frontier = [[initial_state, []]]
  seen = {}

  until frontier.empty?
    state, moves = frontier.shift
    seen[state.to_i] = true
    MOVES.each_with_index { |move, i|
      new_state = state.apply_move(move)
      next if seen[new_state.to_i]
      new_moves = moves + [i]
      return new_moves.freeze if new_state.all? { |x| x == 2 }
      frontier << [new_state, new_moves]
    }
  end
end

best_moves = search(INITIAL_STATE)
state = INITIAL_STATE
best_moves.each { |move|
  state = state.apply_move(MOVES[move])
  puts "Move #{move}"
  state.each_slice(4) { |row| puts row.to_s }
}

output

Move 0
[2, 1, 0, 0]
[1, 2, 2, 0]
[0, 0, 0, 0]
Move 2
[2, 2, 2, 1]
[1, 2, 0, 0]
[0, 0, 0, 0]
Move 7
[2, 2, 2, 2]
[1, 2, 1, 2]
[0, 0, 0, 1]
Move 8
[2, 2, 2, 2]
[2, 2, 1, 2]
[2, 1, 0, 1]
Move 10
[2, 2, 2, 2]
[2, 2, 2, 2]
[2, 2, 2, 2]