Ngoc Le

lib/max_subarray.rb

@@ -1,8 +1,24 @@
 
-# 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.empty?
+    max_so_far = nums.max
+    if max_so_far < 0
+        return max_so_far
+    end
+    max_ending_here = 0
+
+    nums.each do |num|
+        max_ending_here = max_ending_here + num
+
+        if max_ending_here < 0
+            max_ending_here = 0
+        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 +1,20 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+# Time complexity: O(n)
+# Space Complexity: O(n)
+
+
+def newman_conway(nums)
+  result = Array.new()
+  raise ArgumentError if nums == 0
+  return "1" if nums == 1 
+  result[1] = 1
+  result[2] = 1
+  if nums > 2
+    (3..nums).each do |num|
+    result[num] = result[result[num - 1]] + result[num - result[num - 1]]
+    end
+  end
+  result.delete_at(0)
+  return result.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]