class Questions::Issue20260316

Answers::Issue20260316

Question

You’re given a 2D grid representing a city where each cell is either empty (0), a fire station (1), or a building (2). Fire stations can serve buildings based on horizontal + vertical moves only. Return a 2D grid where each cell shows the minimum distance to the nearest fire station.

Examples

Public Instance Methods

setup ()

Source

# File questions/20260316.rb, line 20
def setup
  @methods  = Answers::Issue20260316.instance_methods(false)
  @examples = [
    {
      city_grid: [
        [2, 0, 1],
        [0, 2, 0],
        [1, 0, 2],
      ],
      expected: [
        [2, 1, 0],
        [1, 2, 1],
        [0, 1, 2],
      ],
    },
    {
      city_grid: [
        [1, 0, 0, 1],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [1, 0, 0, 1],
      ],
      expected: [
        [0, 1, 1, 0],
        [1, 2, 2, 1],
        [1, 2, 2, 1],
        [0, 1, 1, 0],
      ],
    },
  ]
end

Tests

Public Instance Methods

test_answers_with_examples ()

Source

# File questions/20260316.rb, line 54
def test_answers_with_examples
  @methods.each do |method|
    @examples.each do |example|
      actual = public_send(method, example[:city_grid].map(&:clone))

      assert_equal example[:expected],        actual,       "Answer #{method} is not correct"
      refute_same  example[:city_grid],       actual,       "Answer #{method} is messing with the outer city grid"
      refute_same  example[:city_grid].first, actual.first, "Answer #{method} is messing with the inner city grid"
    end
  end
end