Space - Faezeh

lib/max_subarray.rb

@@ -1,8 +1,16 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n)
+# Space Complexity: O(1)
 def max_sub_array(nums)
-    return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+    return 0 if nums.nil?
+
+    max_so_far = nums[0]
+    max_ending_here = 0
+
+    nums.each do |n|
+      max_ending_here = [n, max_ending_here + n].max
+      max_so_far = [max_so_far, max_ending_here].max
+    end
+
+    max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,16 @@
+# Time complexity: O(n)
+# Space Complexity: O(n) -> the result array get larger with the number of elements
+def newman_conway(num)
+  raise ArgumentError if num <= 0
+  return "1" if num == 1
 
+  result = [0, 1, 1]
+  i = 3
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  while i <= num
+    result << result[result[i - 1]] + result[i - result[i - 1]]
+    i += 1
+  end
+
+  result[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]