Branches - Emily Ball

lib/max_subarray.rb

@@ -1,8 +1,19 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n)
+# Space Complexity: O(1)
 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]
+    max_ending_here = 0
+
+    nums.each do |num|
+        max_ending_here = max_ending_here + num
+
+        max_ending_here = num if max_ending_here < num
+
+        max_so_far = max_ending_here if max_so_far < max_ending_here
+    end
+
+    return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,28 @@
+# Time complexity: O(n)
+# Space Complexity: O(n)
+def newman_conway(num)
+  raise ArgumentError.new("Invalid input, must be greater than 0") if num < 1
+
+  list = []
+  i = 0
+  until i == num || i == 2
+    list << 1
+    i += 1
+  end
+
+  return list.join(" ") if num < 3
 
+  return nc_helper(num, list).join(" ")
+end
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+def nc_helper(n, list)
+  return 1 if n < 3
+
+  if list[n-2]
+    n_minus_one = list[n-2]
+  else
+    n_minus_one = (nc_helper(n-1, list)).last
+  end
+
+  return list << list[n_minus_one - 1] + list[n - n_minus_one - 1]
 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]