Kelly

lib/max_subarray.rb

@@ -1,8 +1,23 @@
-
-# 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 == []
+
+  max_arr = nums[0]
+  current_max = 0
+  counter = 0
+
+  while counter < nums.length
+    current_max = current_max + nums[counter]
+    if (max_arr < current_max)
+      max_arr = current_max
+    end
+
+    if current_max < 0
+      current_max = 0
+    end
+    counter += 1
+  end
+
+  return max_arr
 end

lib/newman_conway.rb

@@ -1,7 +1,25 @@
+# Time complexity: O(n)
+# Space Complexity: O(n)
+def newman_conway(num)
+  if num < 1
+    raise ArgumentError, "Enter a positive integer"
+  end
 
+  return "1" if num == 1
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  arr = [0, 1, 1]
+
+  sequence = ""
+  sequence << arr[1].to_s + " "
+  sequence << arr[2].to_s + " "
+
+  counter = 3
+
+  while counter <= num
+    arr[counter] = arr[arr[counter - 1]] + arr[counter - arr[counter - 1]]
+    sequence << arr[counter].to_s + " "
+    counter += 1
+  end
+
+  return sequence[0...-1]
+end

test/max_sub_array_test.rb

@@ -1,9 +1,9 @@
 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]
+    input = [-2, 1, -3, 4, -1, 2, 1, -5, 4]
 
     # Act
     answer = max_sub_array(input)
@@ -25,7 +25,7 @@
 
   it "will work with a totally negative array with the largest element at the rear" do
     # Arrange
-    input = [ -4, -5, -6, -7, -3]
+    input = [-4, -5, -6, -7, -3]
 
     # Act
     answer = max_sub_array(input)
@@ -46,14 +46,14 @@
   end
 
   it "will return nil for an empty array" do
-   # Arrange
-   input = []
+    # Arrange
+    input = []
 
-   # Act
-   answer = max_sub_array(input)
+    # Act
+    answer = max_sub_array(input)
 
-   # Assert
-   expect(answer).must_be_nil
+    # Assert
+    expect(answer).must_be_nil
   end
 
   it "will work for [50, -50, 50]" do
@@ -66,5 +66,4 @@
     # Assert
     expect(answer).must_equal 50
   end
-
-end
+end