Vera - Time

lib/max_subarray.rb

@@ -1,8 +1,31 @@
-
-# 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!"
-end
+    return nil if nums.empty?
+    return nums[0] if nums.length == 1
+
+    max_so_far = nums.min
+    max_ending_here = 0
+
+    index = 0
+    pointer2 = 1
+    while index <= nums.length - 1 || pointer2 <= nums.length - 1
+        max_ending_here = max_ending_here + nums[index]
+        if max_ending_here > max_so_far
+            max_so_far = max_ending_here
+            index += 1
+        else
+            max_ending_here = 0
+            max_ending_here = max_ending_here + nums[pointer2]
+            pointer2 += 1
+            index = pointer2
+        end
+    end
+
+    if max_so_far < max_ending_here
+        max_so_far = max_ending_here
+    end
+
+    return max_so_far
+end

lib/newman_conway.rb

@@ -1,7 +1,20 @@
+# Time complexity: o(n)
+# Space Complexity: o(1)
+def newman_conway(num)
+  raise ArgumentError if num == 0
+  return "1" if num == 1
+  return "1 1" if num == 2
 
+  array = [0,1,1]
+  string = ""
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  (3..num).each do |i|
+    array.push(array[array[i - 1]] + array[i - array[i - 1]])
+  end
+
+  (1..array.length - 1).each do |i|
+    array.length - 1 == i ? string << "#{array[i]}" : string << "#{array[i]} "
+  end
+
+  return string
 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]
@@ -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