Leaves - Samantha

lib/max_subarray.rb

@@ -1,8 +1,29 @@
-
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(n)
+# Space Complexity: O(1)
 def max_sub_array(nums)
-    return 0 if nums == nil
+  return 0 if nums == nil
+  return nil if nums.empty?
+
+  max = nums[0]
+  current_sum = 0
+
+  i = 0
+  while i < nums.length
+    current_sum += nums[i]
+
+    if current_sum > max
+      max = current_sum
+    end
+
+    if current_sum < 0
+      current_sum = 0
+    end 
 
-    raise NotImplementedError, "Method not implemented yet!"
+    i += 1
+  end
+
+  return max
 end
+
+
+#pp max_sub_array([-2,1,-3,4,-1,2,1,-5,4])

lib/newman_conway.rb

@@ -1,7 +1,22 @@
+# Time complexity: O(n)
+# Space Complexity: O(n)
+def newman_conway(num)
+  raise ArgumentError if num < 1
+  return "1" if num == 1
+
+  seq = [0, 1, 1]
+  i = 3
+  result = "1 1"
+
+  until i >= num + 1
+    current = seq[seq[i-1]] + seq[i - (seq[i-1])]
+    seq << current
+    result += " #{current}"
+    i += 1
+  end
+
+  return result
+end 
 
 
-# Time complexity: ?
-# Space Complexity: ?
-def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+#pp newman_conway(13)

test/max_sub_array_test.rb

@@ -1,70 +1,70 @@
 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]
-
+    
     # Act
     answer = max_sub_array(input)
-
+    
     # Assert
     expect(answer).must_equal 6
   end
-
+  
   it "will work with a totally negative array" do
     # Arrange
     input = [-3, -4, -5, -6, -7]
-
+    
     # Act
     answer = max_sub_array(input)
-
+    
     # Assert
     expect(answer).must_equal(-3)
   end
-
+  
   it "will work with a totally negative array with the largest element at the rear" do
     # Arrange
     input = [ -4, -5, -6, -7, -3]
-
+    
     # Act
     answer = max_sub_array(input)
-
+    
     # Assert
     expect(answer).must_equal(-3)
   end
-
+  
   it "will work with a 1-element array" do
     # Arrange
     input = [3]
-
+    
     # Act
     answer = max_sub_array(input)
-
+    
     # Assert
     expect(answer).must_equal 3
   end
-
+  
   it "will return nil for an empty array" do
-   # Arrange
-   input = []
-
-   # Act
-   answer = max_sub_array(input)
-
-   # Assert
-   expect(answer).must_be_nil
+    # Arrange
+    input = []
+    
+    # Act
+    answer = max_sub_array(input)
+    
+    # Assert
+    expect(answer).must_be_nil
   end
-
+  
   it "will work for [50, -50, 50]" do
     # Arrange
     input = [50, -50, 50]
-
+    
     # Act
     answer = max_sub_array(input)
-
+    
     # Assert
     expect(answer).must_equal 50
   end
-
-end
+  
+end