Fire - Jing

lib/max_subarray.rb

@@ -1,8 +1,13 @@
 
-# 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!"
+    return nil if nums.nil? || nums.empty?
+    max_sum = - 1.0 / 0
+    current_sum = 0
+    nums.each do |n| 
+        current_sum = [n, current_sum + n].max
+        max_sum = [current_sum, max_sum].max
+    end
+    return max_sum
 end

lib/newman_conway.rb

@@ -1,7 +1,17 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n)
+# Space Complexity: O(n)
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  raise ArgumentError if num < 1
+  p = [0, 1, 1]
+
+  i = 3
+  while i <= num
+    p << p[p[i - 1]] + p[i - p[i - 1]]
+
+    i += 1
+  end
+
+  return p[1..num].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]