Leaves - Yitgop

lib/max_subarray.rb

@@ -1,8 +1,27 @@
+# Time Complexity: O(n)
+# Space Complexity: O(1)
 
-# Time Complexity: ?
-# Space Complexity: ?
 def max_sub_array(nums)
     return 0 if nums == nil
+    return nil if nums == []
 
-    raise NotImplementedError, "Method not implemented yet!"
+    curr_max = nums[0]
+    max_so_far = nums[0]
+
+    i = 1
+    until i == nums.length
+        if curr_max + nums[i] < nums[i]
+            curr_max = nums[i]
+        else
+            curr_max += nums[i]
+        end
+
+        if curr_max > max_so_far
+            max_so_far = curr_max
+        end
+
+        i += 1
+    end
+
+    return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,18 @@
+# Time complexity: O(n)
+# Space Complexity: O(n)
 
-
-# Time complexity: ?
-# Space Complexity: ?
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  raise ArgumentError if num < 1
+  return "1" if num == 1
+  return "1 1" if num == 2
+
+  s = [0, 1, 1]
+  result = "1 1"
+
+  for i in 3..num
+    s[i] = s[s[i - 1]] + s[i - s[i - 1]]
+    result << " #{s[i]}"
+  end
+
+  return result
+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]