diff --git a/lib/max_subarray.rb b/lib/max_subarray.rb index 5204edb..f52cc09 100644 --- a/lib/max_subarray.rb +++ b/lib/max_subarray.rb @@ -1,8 +1,37 @@ -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n), where n is the number of elements inside the nums array +# Space Complexity: O(1), because extra space required isn't determined by input def max_sub_array(nums) - return 0 if nums == nil - - raise NotImplementedError, "Method not implemented yet!" + return nil if nums == [] + return 0 if nums == nil + + max_so_far = 0 + max_ending_here = 0 + max_element = nums[0] + + i = 0 + + while i <= nums.length - 1 + max_ending_here = max_ending_here + nums[i] + + if max_ending_here < 0 + max_ending_here = 0 + end + + if max_so_far < max_ending_here + max_so_far = max_ending_here + end + + if max_element < nums[i] + max_element = nums[i] + end + + i += 1 + end + + if max_so_far == 0 + max_so_far = max_element + end + + return max_so_far end diff --git a/lib/newman_conway.rb b/lib/newman_conway.rb index 4c985cd..6e4c8a5 100644 --- a/lib/newman_conway.rb +++ b/lib/newman_conway.rb @@ -1,7 +1,23 @@ -# Time complexity: ? -# Space Complexity: ? +# Time complexity: O(n), where n is the input +# Space Complexity: O(n), where n is the input 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 + return "1 1" if num == 2 + + conway_numbers = Array.new(num) + conway_numbers[1] = 1 + conway_numbers[2] = 1 + + i = 3 + while i <= num + conway_numbers[i] = conway_numbers[conway_numbers[i - 1]] + conway_numbers[i - (conway_numbers[i - 1])] + + i += 1 + end + + conway_numbers = conway_numbers[1..-1].join(" ") + return conway_numbers +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