Leaves_Ga-Young

lib/max_subarray.rb

@@ -1,8 +1,23 @@
 
-# Time Complexity: ?
-# Space Complexity: ?
+# Time Complexity: O(nums)
+# Space Complexity: O(1)
 def max_sub_array(nums)
     return 0 if nums == nil
 
-    raise NotImplementedError, "Method not implemented yet!"
+    max_so_far = nums[0]
+    max_ending_here = nums[0]
+
+    counter = 1
+    until counter > nums.length - 1 # T: O(nums)
+        max_ending_here = max_ending_here + nums[counter]
+        if max_ending_here < nums[counter]
+            max_ending_here = nums[counter]
+        end
+
+        if max_ending_here > max_so_far
+            max_so_far = max_ending_here
+        end
+        counter += 1
+    end
+    return max_so_far
 end

lib/newman_conway.rb

@@ -1,7 +1,23 @@
-
-
-# Time complexity: ?
-# Space Complexity: ?
+# Time complexity: O(n * num) ?
+# Space Complexity: O(num) ?
 def newman_conway(num)
-  raise NotImplementedError, "newman_conway isn't implemented"
-end
+  newman_conway_helper([0, 1, 1], 3, num)
+end
+
+def newman_conway_helper(p, current, n)
+  if n <= 0
+    raise ArgumentError, "Input must be greater than 0."
+  end
+
+  return "1" if n == 1
+  return "1 1" if n == 2
+
+  if current > n 
+    p.shift # S: O(n)?  T: O(n)?
+    return p.join(" ")
+  end
+
+  p << p[p[current - 1]] + p[current - p[current - 1]]
+
+  return newman_conway_helper(p, current + 1, n) # T: O(num) calls this recursively about num number of times
+end

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

test/newman_conway_test.rb

@@ -4,51 +4,51 @@
   it "works with 13" do
     # Arrange
     input = 13
-
+    
     # Act
     answer = newman_conway(input)
-
+    
     # Assert
     expect(answer).must_equal "1 1 2 2 3 4 4 4 5 6 7 7 8"
   end
-
+  
   it "works with 20" do
     # Arrange
     input = 20
-
+    
     # Act
     answer = newman_conway(input)
-
+    
     # Assert
     expect(answer).must_equal "1 1 2 2 3 4 4 4 5 6 7 7 8 8 8 8 9 10 11 12"
   end
-
+  
   it "works with base cases" do
-        # Arrange
-        input = 0
-
-        # Act-Assert
-        expect {
-          newman_conway(input)
-        }.must_raise ArgumentError
+    # Arrange
+    input = 0
 
-
-        # Arrange
-        input = 1
-
-        # Act
-        answer = newman_conway(input)
+    # Act-Assert
+    expect {
+      newman_conway(input)
+    }.must_raise ArgumentError
 
-        # Assert
-        expect(answer).must_equal "1"
-
-        # Arrange
-        input = 2
-
-        # Act
-        answer = newman_conway(input)
 
-        # Assert
-        expect(answer).must_equal "1 1"        
+    # Arrange
+    input = 1
+
+    # Act
+    answer = newman_conway(input)
+
+    # Assert
+    expect(answer).must_equal "1"
+
+    # Arrange
+    input = 2
+
+    # Act
+    answer = newman_conway(input)
+
+    # Assert
+    expect(answer).must_equal "1 1"        
   end
 end