Branches - Julia Bouvier

lib/max_subarray.rb

@@ -2,7 +2,22 @@
 # Time Complexity: ?
 # Space Complexity: ?
 def max_sub_array(nums)
-    return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+  return 0 if nums == nil
+  return nil if nums.empty?
+
+  max_so_far = max_ending_here = nums[0]
+
+  nums[1..-1].each do |num|
+    if num > max_ending_here + num
+      max_ending_here = num
+    else
+      max_ending_here += num
+    end
+
+    if max_so_far < max_ending_here
+      max_so_far = max_ending_here
+    end
+  end
+
+  return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,21 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n)
+# Space Complexity: O(n)
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  raise ArgumentError if num < 1
+
+  storage = []
+
+  i = 1
+  while i <= num
+    if i < 3
+      storage[i] = 1
+    else
+      storage[i] = storage[storage[i - 1]] + storage[i - storage[i - 1]]
+    end
+    i += 1
+  end
+
+  return storage.join(" ")[1..-1] # fencepost slice
 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]