diff --git a/lib/max_subarray.rb b/lib/max_subarray.rb index 5204edb..70ed8ca 100644 --- a/lib/max_subarray.rb +++ b/lib/max_subarray.rb @@ -1,8 +1,30 @@ -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n) +# Space Complexity: O(1) def max_sub_array(nums) return 0 if nums == nil + return nums[0] if nums.length == 1 + + max = nums[0] + current_sum = nums[0] + + # start at num[1] because max and current_sum already set at num[0] + i = 1 + + while i < nums.length + if nums[i] > current_sum + nums[i] + current_sum = nums[i] + else + current_sum += nums[i] + end + + if max < current_sum + max = current_sum + end + + i += 1 + end + + return max - raise NotImplementedError, "Method not implemented yet!" end diff --git a/lib/newman_conway.rb b/lib/newman_conway.rb index 4c985cd..9e52e08 100644 --- a/lib/newman_conway.rb +++ b/lib/newman_conway.rb @@ -1,7 +1,24 @@ -# Time complexity: ? -# Space Complexity: ? +# Time complexity: O(n) +# Space Complexity: O(n) because I have an array that is being returned as a string. Array and String both have O(n) space complexity def newman_conway(num) - raise NotImplementedError, "newman_conway isn't implemented" + raise ArgumentError if num < 1 + + sequence = [1, 1] + return sequence[1].to_s if num == 1 + return sequence.join(" ") if num == 2 + + # Not sure why it has to start as [0,1,1]? But it works, so.....yeah. + array = [0, 1, 1] + n = 3 + + while n <= num + sequence << array[n] = array[array[n - 1]] + array[n - array[n-1]] + n += 1 + end + + return sequence.join(" ") + + 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]