Sarah

lib/max_subarray.rb

@@ -1,8 +1,14 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) where n is the length of nums, we iterate over the array once, and perform constant time operations each loop
+# Space Complexity: O(1) we only use constant sized variables
 def max_sub_array(nums)
-    return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+  return 0 if nums == nil
+  best_total = nil
+  curr_total = 0
+  nums.each do |num|
+    curr_total += num
+    best_total = curr_total if !best_total or curr_total > best_total
+    curr_total = 0 if curr_total < 0
+  end
+  return best_total
 end

lib/newman_conway.rb

@@ -1,7 +1,18 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n) where n is the size of num
+# Space Complexity: O(n) becuase we are creating a new array of size n
+
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  raise ArgumentError if num <= 0
+  sequence = Array.new(num)
+  num.times do |i|
+    if i < 2
+      sequence[i] = 1
+    else
+      previous = sequence[i - 1]
+      sequence[i] = sequence[previous - 1] + sequence[i - previous]
+    end
+  end
+  return sequence.join(" ")
+end