Branches - Dora

lib/max_subarray.rb

@@ -1,8 +1,30 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n)
+# Space Complexity: O(1)
 def max_sub_array(nums)
     return 0 if nums == nil
+    return nums[0] if nums.length == 1
+
+    max = nums[0]
+    current_sum = nums[0]
+
+    # start at num[1] because max and current_sum already set at num[0]
+    i = 1
+
+    while i < nums.length
+      if nums[i] > current_sum + nums[i]
+        current_sum = nums[i]
+      else
+        current_sum += nums[i]
+      end
+
+      if max < current_sum
+        max = current_sum
+      end
+
+      i += 1
+    end
+
+    return max
 
-    raise NotImplementedError, "Method not implemented yet!"
 end

lib/newman_conway.rb

@@ -1,7 +1,24 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n)
+# Space Complexity: O(n) because I have an array that is being returned as a string. Array and String both have O(n) space complexity
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  raise ArgumentError if num < 1
+
+  sequence = [1, 1]
+  return sequence[1].to_s if num == 1
+  return sequence.join(" ") if num == 2
+
+  # Not sure why it has to start as [0,1,1]? But it works, so.....yeah.
+  array = [0, 1, 1]
+  n = 3
+
+  while n <= num
+    sequence << array[n] = array[array[n - 1]] + array[n - array[n-1]]
+    n += 1
+  end
+
+  return sequence.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]