Rat In A Maze Puzzle [backtracking, ruby]

rat_in_maze.rb

# Given a maze, NxN matrix. A rat has to find a path from source to destination.
# maze[0][0] (left top corner)is the source and maze[N-1][N-1](right bottom corner)
# is destination. There are few cells which are blocked, means rat cannot enter
# into those cells. Rat can move in any direction (left, right, up and down).
require 'rspec/autorun'

class RatInMaze
  def initialize(maze)
    @maze = maze
    @n = maze.size
    @board = Array.new(@n) { Array.new(@n, false) }

    @variantions =
      [[ 1, 0, 'down', 'up'   ],
       [ 0, 1, 'right','left' ],
       [-1, 0, 'up',   'down' ],
       [ 0,-1, 'left', 'right']]
  end

  def solve
    find_path(0, 0, 'down') ? @board : 'NO PATH FOUND'
  end

  def find_path(row, col, direction)
    return false unless can_move?(row, col)

    @board[row][col] = true
    return true if row == @n-1 && col == @n-1

    @variantions.each do |var_row, var_col, new_direction, opposite|
      return true if direction != opposite && find_path(row+var_row, col+var_col, new_direction)
    end

    @board[row][col] = false
    false
  end

  def can_move?(row, col)
    row.between?(0,@n-1) && col.between?(0,@n-1) && @maze[row][col] != 0 && !@board[row][col]
  end
end

RSpec.describe RatInMaze do
  let(:maze) do
    [[ 1, 0, 1, 1, 1 ],
     [ 1, 1, 1, 0, 1 ],
     [ 1, 0, 0, 1, 1 ],
     [ 1, 1, 0, 1, 0 ],
     [ 0, 1, 0, 1, 1 ]]
  end

  let(:result) do
    [[true,  false, true,  true,  true],
     [true,  true,  true,  false, true],
     [false, false, false, true,  true],
     [false, false, false, true,  false],
     [false, false, false, true,  true]]
  end

  it '#solve' do
    r = RatInMaze.new(maze)
    expect(r.solve).to eq result
  end
end