Sara Nilsen - Space

lib/max_subarray.rb

@@ -1,8 +1,18 @@
 
-# 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 nil if nums.nil? || nums.empty? 
+
+    max_so_far = nums[0]
+    max_ending_here = nums[0]
+    i = 1
+
+    while i < nums.length 
+        max_ending_here = [nums[i], (max_ending_here + nums[i])].max
+        max_so_far = [max_so_far, max_ending_here].max
+        i += 1
+    end 
+
+    return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,25 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n)
+# Space Complexity: O(n)
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  s = [0, 1, 1]
+  i = 3 
+
+  if num == 0 
+    raise ArgumentError, "Number should be greater or equal to 1"
+  elsif num == 1 
+    return "1"
+  elsif num == 2 
+    return "1 1"
+  else 
+    while i <= num 
+      s[i] = s[s[i - 1]] + s[i - s[i - 1]]
+      i += 1 
+    end 
+  end 
+  # remove first element and return the sequence as string 
+
+  return s.drop(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]