Jansen

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

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
+  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

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
+end