Branches- Erika

lib/recursive-methods.rb

@@ -1,49 +1,101 @@
-# Authoring recursive algorithms. Add comments including time and space complexity for each method.
+# # # # # 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"
+
+  raise ArgumentError unless n >= 0 
+  return 1 if n == 1 || n == 0
+
+  n * factorial(n - 1)
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# # # # Time complexity: O(n)
+# # # # Space complexity: O(n) maybe less?
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+
+  return s if s.length <= 1
+  reversed = reverse(s[1..-1])
+  reversed << s[0]
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+
+# # # # # Time complexity: O(n)
+# # # # # Space complexity: O(n)
+def reverse_inplace(s, pointer = 0)
+
+    return s if pointer == s.length / 2
+    s[pointer], s[- 1 - pointer] = s[- 1 - pointer ], s[pointer]
+
+    reverse_inplace(s, pointer + 1)
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# # # # Time complexity: O(n)
+# # # # Space complexity: O(n)
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+
+    return 0 if n == 0
+    return 2 if n == 1
+    bunny(n - 1) + 2
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def nested(s)
-    raise NotImplementedError, "Method not implemented"
+
+# # # Time complexity: O(n) 
+# # # Space complexity: O(n)
+
+def nested(s, i = 0, j = s.length - 1)
+
+    return false if s.length.odd? 
+    return false if s[i] == "(" && s[j] != ")" || (s[i] == ")" && i < j)
+    return true if i > j || s.empty?
+
+
+    nested(s, i + 1, j - 1)
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+
+# # # # Time complexity: O(n)
+# # # # Space complexity: O(n)
+def search(array, value, i = 0)
+
+    return true if array[i] == value
+    return false if i == array.length
+    search(array, value, i + 1)
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+
+# # # # # Time complexity: O(n)
+# # # # # Space complexity: O(n)
+
+def is_palindrome(s, i = 0, j = -1)
+
+    return false if s[i] != s[j]
+    return true if i > s.length - 1
+
+    is_palindrome(s, i + 1, j - 1)
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
-end
+# # # Time complexity: O(n)
+# # # Space complexity: O(n)
+def digit_match(n, m, matches = 0)
+
+    dig1 = n % 10
+    dig2 = m % 10
+
+    return matches if n == 0 || m == 0
+    matches += 1 if dig1 == dig2 
+
+    n = n / 10
+    m = m / 10
+    digit_match(n, m, matches)
+
+end

test/recursion_writing_test.rb

@@ -1,8 +1,10 @@
 require 'minitest/autorun'
-require 'minitest/reporters'
-require "minitest/skip_dsl"
+# require 'minitest/reporters'
+# require "minitest/skip_dsl"
 require_relative '../lib/recursive-methods'
 
+# Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
+
 describe "factorial" do
   it "will find the factorial of 0" do
     # Arrange
@@ -38,7 +40,7 @@
   end
 end
 
-xdescribe "reverse" do
+describe "reverse" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -84,7 +86,7 @@
 end
 
 
-xdescribe "reverse_in_place" do
+describe "reverse_in_place" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -129,7 +131,7 @@
   end
 end
 
-xdescribe "bunny" do
+describe "bunny" do
   it "returns 0 for 0 bunnies" do
     # Arrange
     count = 0
@@ -164,7 +166,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""
@@ -210,7 +212,7 @@
   end
 end
 
-xdescribe "search" do
+describe "search" do
   it "will return false for empty array" do
     # Arrange
     item = "a"
@@ -260,7 +262,7 @@
     end      
 end
 
-xdescribe "is_palindrome" do
+describe "is_palindrome" do
   it "will return true for emptystring" do
     # Arrange
     string = ""
@@ -295,64 +297,64 @@
   end
 end
 
-xdescribe "digit_match" do
-  it "returns 4 for 1072503891 and 62530841" do
-    # Arrange
-    num1 = 1072503891
-    num2 = 62530841
+# xdescribe "digit_match" do
+#   it "returns 4 for 1072503891 and 62530841" do
+#     # Arrange
+#     num1 = 1072503891
+#     num2 = 62530841
 
-    # Act
-    answer = digit_match(num1, num2)
+#     # Act
+#     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 4
-  end
+#      # Assert
+#      expect(answer).must_equal 4
+#   end
 
-  it "returns 0 for nonmatching numbers" do
-    # Arrange
-    num1 = 0
-    num2 = 62530841
+#   it "returns 0 for nonmatching numbers" do
+#     # Arrange
+#     num1 = 0
+#     num2 = 62530841
 
-    # Act
-    answer = digit_match(num1, num2)
+#     # Act
+#     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 0
-  end
+#      # Assert
+#      expect(answer).must_equal 0
+#   end
 
-  it "returns 3 for 841 and 62530841" do
-    # Arrange
-    num1 = 841
-    num2 = 62530841
+#   it "returns 3 for 841 and 62530841" do
+#     # Arrange
+#     num1 = 841
+#     num2 = 62530841
 
-    # Act
-    answer = digit_match(num1, num2)
+#     # Act
+#     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 3
-  end
+#      # Assert
+#      expect(answer).must_equal 3
+#   end
 
-  it "returns 1 for (0, 0)" do
-    # Arrange
-    num1 = 0
-    num2 = 0
+#   it "returns 1 for (0, 0)" do
+#     # Arrange
+#     num1 = 0
+#     num2 = 0
 
-    # Act
-    answer = digit_match(num1, num2)
+#     # Act
+#     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 1
-  end
+#      # Assert
+#      expect(answer).must_equal 1
+#   end
 
-  it "returns 1 for (10, 20)" do
-    # Arrange
-    num1 = 10
-    num2 = 20
-
-    # Act
-    answer = digit_match(num1, num2)
-
-     # Assert
-     expect(answer).must_equal 1
-  end
-end
+#   it "returns 1 for (10, 20)" do
+#     # Arrange
+#     num1 = 10
+#     num2 = 20
+
+#     # Act
+#     answer = digit_match(num1, num2)
+
+#      # Assert
+#      expect(answer).must_equal 1
+#   end
+# end