Sockets - Nara

lib/recursive-methods.rb

@@ -1,49 +1,94 @@
 # 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"
+  if n == 0 || n == 1
+    return 1
+  elsif n < 0
+    raise ArgumentError.new("Parameter must be a positive number")
+  else
+    return n * factorial(n - 1)
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(2^n)
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length <= 1
+    return s
+  else
+    return s[-1] + reverse(s[0...-1])
+  end
 end
 
+
 # Time complexity: ?
 # Space complexity: ?
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+  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 n
+    else
+      return 2 + bunny(n-1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# Time complexity: O(n)
+# Space complexity: O(n^2)
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
+  if s == ""
+    return true
+  end
+  if s[0] != "(" || s[-1] != ")"
+    return false
+  end
+  return nested(s[1...-1])
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n^2)
 def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+  if array.length == 0
+    return false
+  end
+  if value == array[0]
+    return true
+  else
+    return search(array[1..-1], value)
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# Time complexity: O(n)
+# Space complexity: O(2^n)
 def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+  if s == ""
+    return true
+  end
+  if s[0] != s[-1]
+    return false
+  end
+  return is_palindrome(s[1...-1])
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(1)
 def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
+  if n == 0 || m == 0
+    return 0
+  end
+  if n%10 == m%10
+    value = 1
+  else
+    value = 0
+  end
+  return value + digit_match(n/10, m/10)
 end

specs/recursion_writing_spec.rb

@@ -27,6 +27,7 @@
 
   end
 
+
   it "will raise an ArgumentError if given a number not >= 0" do
     # Arrange
     num = -1
@@ -38,7 +39,7 @@
   end
 end
 
-xdescribe "reverse" do
+describe "reverse" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -129,7 +130,7 @@
   end
 end
 
-xdescribe "bunny" do
+describe "bunny" do
   it "returns 0 for 0 bunnies" do
     # Arrange
     count = 0
@@ -164,7 +165,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""
@@ -210,7 +211,7 @@
   end
 end
 
-xdescribe "search" do
+describe "search" do
   it "will return false for empty array" do
     # Arrange
     item = "a"
@@ -260,7 +261,7 @@
     end      
 end
 
-xdescribe "is_palindrome" do
+describe "is_palindrome" do
   it "will return true for emptystring" do
     # Arrange
     string = ""
@@ -295,7 +296,7 @@
   end
 end
 
-xdescribe "digit_match" do
+describe "digit_match" do
   it "returns 4 for 1072503891 and 62530841" do
     # Arrange
     num1 = 1072503891