Daniela - Leaves

lib/max_subarray.rb

@@ -1,8 +1,25 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n), I just iterate over the array one time.
+# Space Complexity: O(1) as I'm always storing the last_max and max_ending_here and these are always an integer.
 def max_sub_array(nums)
     return 0 if nums == nil
-
-    raise NotImplementedError, "Method not implemented yet!"
+    return nil if nums == []
+
+    current_max = nums[0]
+    max_ending_here = 0
+
+    nums.each do |number|
+      max_ending_here += number
+
+      if current_max < max_ending_here
+        current_max = max_ending_here
+      elsif (max_ending_here < 0)
+        if current_max < number
+          current_max = number
+        end
+        max_ending_here = 0
+      end
+    end
+
+  return current_max
 end

lib/newman_conway.rb

@@ -1,7 +1,37 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n) to create the array with the results 
+# + O(n) to get each value of the array = 2*O(n) =~ O(n)
+# Space Complexity: O(n) as I will need to create an array with n elements and this is constant. 
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  raise ArgumentError if num <= 0
+  f = []
+
+  if num == 1
+    return "1"
+  elsif num == 2
+    return "1 1"
+  else 
+    f = [0,1,1]
+    i = 3 
+
+    while i <= num 
+      f << f[f[i - 1]] + f[i - f[i - 1]]
+      i += 1
+    end
+
+    string_results = ""
+    iteration = 0
+    f = f[1..-1]
+
+    f.each do |result|
+      iteration +=1
+      if f.length == iteration
+        string_results += "#{result}"
+      else
+        string_results += "#{result}" + " "
+      end
+    end
+    return string_results
+  end
 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]