Rachael --Final Water Showdown

lib/max_subarray.rb

@@ -1,8 +1,21 @@
 
-# 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!"
+    if nums.empty? 
+        return nil
+    end
+    max_so_far = nums[0]
+    max_ending_here = 0
+
+    nums.each do |num|
+        max_ending_here += num
+        if max_so_far < max_ending_here
+            max_so_far = max_ending_here
+        elsif max_ending_here < 0
+            max_ending_here = 0
+        end
+
+    end
+    return max_so_far
 end

lib/newman_conway.rb

@@ -3,5 +3,26 @@
 # Time complexity: ?
 # Space Complexity: ?
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  if num == 0
+    raise ArgumentError
+  end
+  if num == 1
+    return "1"
+  end
+
+  array = []
+  array[0] = 0
+  array[1] = 1
+  array[2] = 1
+
+  i = 3
+
+  while i <= num
+    array[i] = array[array[i-1]] + array[i - array[i - 1]]
+    i += 1
+  end
+
+  array.slice!(0)
+
+  return array.join(',').gsub(',', ' ')
 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]