Raisah

lib/max_subarray.rb

@@ -1,8 +1,18 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
-def max_sub_array(nums)
-    return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+# Time Complexity: O(n) because the each loop will iterate through each item in the array
+# Space Complexity: O(1) there are no additional data structures or recursive calls to add to space complexity
+def max_sub_array(array)
+  return nil if array.empty?
+  return array.first if array.length == 1
+
+  max_so_far = array[0]
+  max_ending_here = array[0]
+
+  (1..array.length - 1).each do |i|
+    max_ending_here = [array[i], max_ending_here + array[i]].max
+    max_so_far = [max_ending_here, max_so_far].max
+  end
+
+  return max_so_far
 end
+

lib/newman_conway.rb

@@ -1,7 +1,18 @@
+# Time complexity: O(n) because the each loop is run n times
+# Space Complexity: O(n) because there is an additional array solutions that varies linearly with size of n
+def newman_conway(terms)
+  raise ArgumentError if terms < 1
 
+  solutions = [nil]
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  (1..terms).each do |n|
+    if n < 3
+      solutions << 1
+    else
+      solutions << (solutions[solutions[n - 1]] + solutions[n - solutions[n - 1]])
+    end
+  end
+
+  solutions.shift
+  return solutions.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]