class Questions::Issue20260309

Answers::Issue20260309

Question

Given a string s consisting only of ‘a’ and ‘b’, you may swap adjacent characters any number of times. Return the minimum number of adjacent swaps needed to transform s into an alternating string, either “ababab…” or “bababa…”, or return -1 if it’s impossible.

Examples

Public Instance Methods

setup ()

Source

# File questions/20260309.rb, line 22
def setup
  @methods  = Answers::Issue20260309.instance_methods(false)
  @examples = [
    {
      string: "aabb",
      expected: 1,
    },
    {
      string: "aaaabbbb",
      expected: 6,
    },
    {
      string: "aaab",
      expected: -1,
    },
    # Extra examples by izkreny
    {
      string: "ba",
      expected: 0,
    },
    {
      string: "baa",
      expected: 1,
    },
    {
      string: "bbbaa",
      expected: 3,
    },
  ]
end

Tests

Public Instance Methods

test_answers_with_examples ()

Source

# File questions/20260309.rb, line 55
def test_answers_with_examples
  @methods.each do |method|
    @examples.each do |example|
      actual = public_send(method, example[:string])

      assert_equal example[:expected], actual, "Answer #{method} is not correct for '#{example[:string]}' string"
      refute_same  example[:string],   actual, "Answer #{method} is messing with the string"
    end
  end
end