diff --git a/lib/max_subarray.rb b/lib/max_subarray.rb index 5204edb..8fbbc0e 100644 --- a/lib/max_subarray.rb +++ b/lib/max_subarray.rb @@ -1,8 +1,19 @@ -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n) +# Space Complexity: O(1) def max_sub_array(nums) - return 0 if nums == nil + return nil if nums.nil? || nums.empty? - raise NotImplementedError, "Method not implemented yet!" + max_so_far = nums[0] + max_ending_here = 0 + + nums.each do |num| + max_ending_here = max_ending_here + num + + max_ending_here = num if max_ending_here < num + + max_so_far = max_ending_here if max_so_far < max_ending_here + end + + return max_so_far end diff --git a/lib/newman_conway.rb b/lib/newman_conway.rb index 4c985cd..6bf4096 100644 --- a/lib/newman_conway.rb +++ b/lib/newman_conway.rb @@ -1,7 +1,28 @@ +# Time complexity: O(n) +# Space Complexity: O(n) +def newman_conway(num) + raise ArgumentError.new("Invalid input, must be greater than 0") if num < 1 + + list = [] + i = 0 + until i == num || i == 2 + list << 1 + i += 1 + end + + return list.join(" ") if num < 3 + return nc_helper(num, list).join(" ") +end -# Time complexity: ? -# Space Complexity: ? -def newman_conway(num) - raise NotImplementedError, "newman_conway isn't implemented" +def nc_helper(n, list) + return 1 if n < 3 + + if list[n-2] + n_minus_one = list[n-2] + else + n_minus_one = (nc_helper(n-1, list)).last + end + + return list << list[n_minus_one - 1] + list[n - n_minus_one - 1] end \ No newline at end of file diff --git a/test/max_sub_array_test.rb b/test/max_sub_array_test.rb index 3253cdf..e27e1ca 100644 --- a/test/max_sub_array_test.rb +++ b/test/max_sub_array_test.rb @@ -1,6 +1,6 @@ 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]