Heather

lib/max_subarray.rb

@@ -1,8 +1,22 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(1), where n is the number of elements in the array
+# Space Complexity: O(1)
 def max_sub_array(nums)
-    return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+  return 0 if nums == nil
+
+  max = nums[0]
+  max_here = 0
+
+  nums.each do |num|
+    max_here += num
+    if max_here > max
+      max = max_here
+    end
+
+    if max_here < 0
+      max_here = 0
+    end
+  end
+
+  return max
 end

lib/newman_conway.rb

@@ -1,7 +1,34 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n), where n is approx. equal to num
+# Space Complexity: O(n), where n is approx. equal to num for the series array & series_string
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  if num == 0
+    raise ArgumentError, "Num cannot be zero"
+  end
+
+  p1 = 1
+  p2 = 1
+  counter = 2
+
+  series = [0, p1, p2]
+  series_string = ""
+
+  if num < 2
+    series[1..num].each do |num|
+      series_string += "#{num} "
+    end
+  else
+    until counter == num
+      counter += 1
+      p_next = series[series[counter - 1]] + series[counter - series[counter - 1]]
+      series << p_next
+    end
+
+    series[1..-1].each do |num|
+      series_string += "#{num} "
+    end
+  end
+
+  return series_string.strip
+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