Branches - Eve

lib/fibonacci.rb

@@ -1,8 +1,22 @@
 # Improved Fibonacci
 
-# Time Complexity - ?
-# Space Complexity - ?  (should be O(n))
+# Time Complexity - O(n)
+# Space Complexity - O(n) stack space
 # Hint, you may want a recursive helper method
 def fibonacci(n)
-
+  return fib_helper([0, 1], 2, n)
 end
+
+def fib_helper(results, current, n)
+  raise ArgumentError if n < 0
+  return results[n] if n == 0 || n == 1
+
+  if current == n
+    return results[0] + results[1]
+  end
+
+  temp = results[0] + results[1]
+  results[0] = results[1]
+  results[1] = temp
+  return fib_helper(results, current + 1, n)
+end

lib/super_digit.rb

@@ -1,15 +1,26 @@
 # Superdigit
 
-# Time Complexity - ?
-# Space Complexity - ?
+# Time Complexity - O(logn) n is the number itself
+# Space Complexity - O(logn)
 def super_digit(n)
-
+    return n if n/10 == 0
+
+    sum = n % 10
+    while n/10 != 0
+        n = n/10
+        sum += n % 10
+    end
+    return super_digit(sum)
 end
-
 
-# Time Complexity - ?
-# Space Complexity - ?
+
+# Time Complexity - O(logn) n is the number itself
+# Space Complexity - O(logn)
 def refined_super_digit(n, k)
-
+    return n if k == 1 && n/10 == 0
+    sum = 0
+    k.times do
+        sum += super_digit(n)
+    end
+    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)