Yasmin-Leaves

lib/max_subarray.rb

@@ -1,8 +1,33 @@
 
-# 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 0 if nums == nil
+    # raise NotImplementedError, "Method not implemented yet!"
+  max_so_far = nums[0]
+  max_ending_here = 0
+
+  nums.each do |num|
+    max_ending_here = max_ending_here + num
+    if max_ending_here < num
+      max_ending_here = num
+    end
+    if max_so_far < max_ending_here
+      max_so_far = max_ending_here
+    end
+  end
+  return max_so_far
 end
+
+#   Initialize:
+#     max_so_far = 0
+#     max_ending_here = 0
+
+# Loop for each element of the array
+#   (a) max_ending_here = max_ending_here + a[i]
+#   (b) if(max_ending_here < 0)
+#             max_ending_here = 0
+#   (c) if(max_so_far < max_ending_here)
+#             max_so_far = max_ending_here
+# return max_so_far

lib/newman_conway.rb

@@ -1,7 +1,23 @@
 
+# Time complexity: o(n)
+# Space Complexity: o(n)
 
-# Time complexity: ?
-# Space Complexity: ?
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  # raise NotImplementedError, "newman_conway isn't implemented"
+  raise ArgumentError if num < 1
+  return "1" if num == 1
+  return "1 1" if num == 2
+
+  newman_conway = [0, 1, 1]
+  sequence = "1 1"
+
+  i = 3
+
+  while i <= num 
+    #p(i) = p(p(i-1)) + p(i - p(i - 1))
+    newman_conway[i] = newman_conway[newman_conway[i - 1]] + newman_conway [i - newman_conway[i - 1]]
+    sequence += " #{newman_conway[i]}"
+    i += 1
+  end
+  return sequence
 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]