Time - Hannah J.

lib/max_subarray.rb

@@ -1,8 +1,16 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) => because I iterate depending on the input (nums)
+# Space Complexity: O(1) => because I use the constant numbers of the space (2 variables)
 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]
+    current_max = nums[0]
+
+    nums[1..-1].each do |current_num|
+        current_max = [current_num, current_num + current_max].max 
+        max_so_far = [current_max, max_so_far].max
+    end
+
+    return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,21 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+# Time complexity: O(n) => because I iterate depending on the input (num)
+# Space Complexity: O(n) => because I create a new array depending on the input (num)
+
+def newman_conway(num) # 9
+  raise ArgumentError if num == 0 
+  solution = []
+
+  (1..num).each do |n|
+    if n == 1 || n == 2
+      solution[n] = 1 
+    else 
+      # P(P(n - 1)) + P(n - P(n - 1))
+      solution[n] = solution[solution[n - 1]] + solution[n - solution[n - 1]]
+    end 
+
+  end 
+
+  return solution[1..-1].join(" ")
 end

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]
@@ -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