Rachael Water

lib/recursive-methods.rb

@@ -1,49 +1,94 @@
+# frozen_string_literal: true
+
 # Authoring recursive algorithms. Add comments including time and space complexity for each method.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+
+  return 1 if n <= 1
+
+
+  n * factorial(n - 1)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+  return s if s.length <= 1
+
+  reversed_str = reverse(s[1..-1])
+  reversed_str += s[0]
+  reversed_str
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(1)
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+    if n == 0
+        return 0
+    else
+         2 * bunny(n-1)
+         return
+    end
+
+    return answer
+
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
+    # if s == ""
+    #     return true
+    # elsif s.length % 2 != 0
+    #     return false
+    # else
+    #     return nested(s)
+    # end
 end
 
-# Time complexity: ?
+# Time complexity: O(n)
 # Space complexity: ?
 def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+  n = 0
+  length = array.length
+  while array[n] != value
+      n += 1
+      search(array, value)
+      if n = length
+          return false
+      end
+  end
+  return true
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
 def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length < 2
+    true
+  elsif s[0] != s[-1]
+    false
+  else
+    is_palindrome(s[1..-2])
+  end
 end
 
 # Time complexity: ?
 # Space complexity: ?
-def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
-end
+def digit_match(n, m, num_matches = 0)
+    # n = n.to_s
+    # m = m.to_s
+    # if n < 10 || m < 10
+    #     return num_matches
+    # else
+    #     return digit_match(n/10, m/10, num_matches = 0)
+    # end
+end

test/recursion_writing_test.rb

@@ -167,7 +167,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""
@@ -213,7 +213,7 @@
   end
 end
 
-xdescribe "search" do
+describe "search" do
   it "will return false for empty array" do
     # Arrange
     item = "a"
@@ -263,7 +263,7 @@
     end      
 end
 
-xdescribe "is_palindrome" do
+describe "is_palindrome" do
   it "will return true for emptystring" do
     # Arrange
     string = ""
@@ -298,7 +298,7 @@
   end
 end
 
-xdescribe "digit_match" do
+describe "digit_match" do
   it "returns 4 for 1072503891 and 62530841" do
     # Arrange
     num1 = 1072503891