diff --git a/lib/max_subarray.rb b/lib/max_subarray.rb index 5204edb..9603e44 100644 --- a/lib/max_subarray.rb +++ b/lib/max_subarray.rb @@ -1,8 +1,23 @@ -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n) - where n is equal to the length of nums - 1 +# Space Complexity: O(1) - constant def max_sub_array(nums) - return 0 if nums == nil - - raise NotImplementedError, "Method not implemented yet!" + return nil if nums == nil || nums.empty? + + current_sum = nums.first + max = nums.first + + (1...nums.length).each do |i| + current_sum += nums[i] + + if current_sum > max + max = current_sum + end + + if current_sum < 0 + current_sum = 0 + end + end + + return max end diff --git a/lib/newman_conway.rb b/lib/newman_conway.rb index 4c985cd..6bdaaff 100644 --- a/lib/newman_conway.rb +++ b/lib/newman_conway.rb @@ -1,7 +1,20 @@ - -# Time complexity: ? -# Space Complexity: ? +# Time complexity: O(n) - where n equals num - 2 +# Space Complexity: O(n) - where n equals num * 2 (for the space needed for the string and the array) def newman_conway(num) - raise NotImplementedError, "newman_conway isn't implemented" -end \ No newline at end of file + raise ArgumentError if num <= 0 + return "1" if num == 1 + + newman = [0, 1, 1] + result = "1 1" + i = 3 + + until i >= num + 1 + current_newman = newman[newman[i - 1]] + newman[i - (newman[i - 1])] + newman << current_newman + result += " #{current_newman}" + i += 1 + end + + return result +end diff --git a/test/max_sub_array_test.rb b/test/max_sub_array_test.rb index 3253cdf..c83ef94 100644 --- a/test/max_sub_array_test.rb +++ b/test/max_sub_array_test.rb @@ -1,9 +1,9 @@ require_relative "test_helper" -xdescribe "max subarray" do +describe "max subarray" do it "will work for [-2,1,-3,4,-1,2,1,-5,4]" do # Arrange - input = [-2,1,-3,4,-1,2,1,-5,4] + input = [-2, 1, -3, 4, -1, 2, 1, -5, 4] # Act answer = max_sub_array(input) @@ -25,7 +25,7 @@ it "will work with a totally negative array with the largest element at the rear" do # Arrange - input = [ -4, -5, -6, -7, -3] + input = [-4, -5, -6, -7, -3] # Act answer = max_sub_array(input) @@ -46,14 +46,14 @@ end it "will return nil for an empty array" do - # Arrange - input = [] + # Arrange + input = [] - # Act - answer = max_sub_array(input) + # Act + answer = max_sub_array(input) - # Assert - expect(answer).must_be_nil + # Assert + expect(answer).must_be_nil end it "will work for [50, -50, 50]" do @@ -66,5 +66,4 @@ # Assert expect(answer).must_equal 50 end - -end \ No newline at end of file +end diff --git a/test/newman_conway_test.rb b/test/newman_conway_test.rb index 537d376..5476d10 100644 --- a/test/newman_conway_test.rb +++ b/test/newman_conway_test.rb @@ -24,31 +24,30 @@ end it "works with base cases" do - # Arrange - input = 0 - - # Act-Assert - expect { - newman_conway(input) - }.must_raise ArgumentError - - - # Arrange - input = 1 - - # Act - answer = newman_conway(input) - - # Assert - expect(answer).must_equal "1" - - # Arrange - input = 2 - - # Act - answer = newman_conway(input) - - # Assert - expect(answer).must_equal "1 1" + # Arrange + input = 0 + + # Act-Assert + expect { + newman_conway(input) + }.must_raise ArgumentError + + # Arrange + input = 1 + + # Act + answer = newman_conway(input) + + # Assert + expect(answer).must_equal "1" + + # Arrange + input = 2 + + # Act + answer = newman_conway(input) + + # Assert + expect(answer).must_equal "1 1" end end