Oddly Zen

def fudgify_duplicates(points)
  points.inject(Array.new) do |fudged, point|
    fudged << if (prev = fudged.last) and prev.first >= point.first
      [prev.first + 1, point.last]
    else
      point
    end
  end
end

if __FILE__ == $PROGRAM_NAME
  require "test/unit"

  class TestFudgifyDuplicates < Test::Unit::TestCase
    def test_no_changes
      assert_fudges_to(Array.new,        Array.new)
      assert_fudges_to([[1, 1], [2, 1]], [[1, 1], [2, 1]])
    end

    def test_simple_additions
      assert_fudges_to([[1, 1], [2, 2]], [[1, 1], [1, 2]])
      # the original version fails the following
      assert_fudges_to([[1, 1], [2, 2], [3, 3]], [[1, 1], [1, 2], [2, 3]])
    end

    def test_tricky_less_than_addition
      # the original version fails the following
      assert_fudges_to([[1, 1], [2, 2], [3, 3]], [[1, 1], [1, 2], [1, 3]])
    end

    def test_jims_example
      assert_fudges_to(
        [ [0, 3777], [31, 3254], [33, 2448], [34, 1752],
          [36, 389], [56, 259],  [100, 726] ],
        [ [0, 3777], [31, 3254], [33, 2448], [33, 1752],
          [36, 389], [56, 259],  [100, 726] ]
      )
    end

    private

    def assert_fudges_to(expected, actual)
      assert_equal(expected, fudgify_duplicates(actual))
    end
  end
end