Earth - Jasmine

lib/max_subarray.rb

@@ -1,8 +1,25 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n) where n = nums
+# Space Complexity: O(1) only storing integers
 def max_sub_array(nums)
     return 0 if nums == nil
+    return nil if nums.empty?
 
-    raise NotImplementedError, "Method not implemented yet!"
+    max_so_far = nums[0]
+    max_ending_here = 0
+
+    nums.each do |num|
+
+        if max_ending_here < 0
+            max_ending_here = num
+        else
+            max_ending_here += num
+        end
+
+        if max_ending_here > max_so_far
+            max_so_far = max_ending_here
+        end
+
+    end
+    return max_so_far    
 end

lib/newman_conway.rb

@@ -1,7 +1,18 @@
 
 
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n) where n is num 
+# Space Complexity: O(n) function stack call & array of (n) values
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
+  return newman_helper(num, 3, [0, 1, 1]).slice(1, num).join(" ")
+end
+
+def newman_helper(num, current, memo)
+  raise ArgumentError if num == 0
+  if current > 2 && current <= num
+    current_idx = current 
+    memo[current_idx] = memo[memo[current_idx - 1]] + memo[current_idx - memo[current_idx - 1]]
+    newman_helper(num, current + 1, memo)
+  end
+
+  return memo
 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]
@@ -67,4 +67,26 @@
     expect(answer).must_equal 50
   end
 
+  it "will work for [-2,1]" do
+    # Arrange
+    input = [-2,1]
+
+    # Act
+    answer = max_sub_array(input)
+
+    # Assert
+    expect(answer).must_equal 1
+  end
+
+  it "will work for [-3,-2,0,-1]" do
+    # Arrange
+    input = [-3,-2,0,-1]
+
+    # Act
+    answer = max_sub_array(input)
+
+    # Assert
+    expect(answer).must_equal 0
+  end
+
 end