Branches - Emily Ball

lib/fibonacci.rb

@@ -1,8 +1,24 @@
 # Improved Fibonacci
 
-# Time Complexity - ?
-# Space Complexity - ?  (should be O(n))
+# Time Complexity - ? 
+# Space Complexity - ?  O(n)
 # Hint, you may want a recursive helper method
-def fibonacci(n)
-
+
+def fib_helper(solutions, current, n)
+  raise ArgumentError.new("negative input") if n < 0
+  return n if n == 0 || n == 1
+
+  if current == n
+    return solutions[0] + solutions[1]
+  end
+
+  temp = solutions[0]
+  solutions[0] = solutions[1] 
+  solutions[1] = temp + solutions[1]
+
+  return fib_helper(solutions, current + 1, n)
 end
+
+def fibonacci(n)
+  return fib_helper([0, 1], 2, n)
+end

lib/super_digit.rb

@@ -1,15 +1,29 @@
 # Superdigit
 
-# Time Complexity - ?
-# Space Complexity - ?
+# Time Complexity - O(n)
+# Space Complexity - O(n)
+
+def digit_sum(n, sum = 0)
+  return n if n < 10
+
+  n.to_s.each_char { |num| sum += num.to_i }
+  return sum
+end
+
 def super_digit(n)
-
+  return n if n < 10
+  return super_digit(digit_sum(n))
 end
 
 
-# Time Complexity - ?
-# Space Complexity - ?
-def refined_super_digit(n, k)
-
-end
-
+# Time Complexity - O(n)
+# Space Complexity - O(n)
+def refined_super_digit(n, k, i = 0)
+  return n if n < 10 
+
+  sum = digit_sum(n)
+  sum *= k if i == 0
+  i += 1
+
+  return super_digit(sum)
+end

test/super_digit_test.rb

@@ -1,6 +1,6 @@
 require_relative "test_helper"
 
-xdescribe "super_digit" do
+describe "super_digit" do
   it "will return 2 for super_digit(9875)" do
     # Act
     answer = super_digit(9875)
@@ -15,7 +15,7 @@
 
     # Assert
     expect(answer).must_equal 5
-   end
+  end
 
   it "will return 6 for super_digit(123)" do
     # Act

test/test_helper.rb

@@ -1,7 +1,7 @@
 require 'minitest'
 require 'minitest/autorun'
 require 'minitest/reporters'
-require "minitest/skip_dsl"
+# require "minitest/skip_dsl"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new