Ports - Heather

lib/recursive-methods.rb

@@ -3,47 +3,81 @@
 # Time complexity: ?
 # Space complexity: ?
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+  if n == 0
+    return 1
+  elsif n == -1
+    raise ArgumentError, "cannot calculate for a negative number"
+  else
+    return n * factorial(n - 1)
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n), where n is equal to the number passed
+# Space complexity: O(n), where n is equal to the number passed
+
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length <= 1
+    return s
+  else
+    return s[-1] + reverse(s[0..-2])
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n), n is the number of characters in the string
+# Space complexity: O(n), n is the number of characters in the string
+
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+  #will need a helper method
+  if s == ""
+    return s
+  end
+
+  temp = s[0]
+  s[0] = s[s.length - 1]
+  s[s.length - 1] = temp
+
+  if s.length > 1
+    s[1..-2] = reverse_inplace(s[1..-2])
+  end
+  return s
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+  if n == 0
+    return 0
+  else
+    return 2 + bunny(n - 1)
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) where n is the number of bunnies
+# Space complexity: O(n) where n is the number of bunnies
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
+  if s == "" || s == "()"
+    return true
+  elsif s[0] == "(" && s[-1] == ")" && nested(s[1..-2])
+    return true
+  else
+    return false
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) where n is the length of the string
+# Space complexity: O(n) where n is the length of the string
 def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+  raise NotImplementedError, "Method not implemented"
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+  raise NotImplementedError, "Method not implemented"
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
-end
+  raise NotImplementedError, "Method not implemented"
+end

specs/recursion_writing_spec.rb

@@ -1,7 +1,7 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
+require "minitest/autorun"
+require "minitest/reporters"
 require "minitest/skip_dsl"
-require_relative '../lib/recursive-methods'
+require_relative "../lib/recursive-methods"
 
 describe "factorial" do
   it "will find the factorial of 0" do
@@ -23,8 +23,7 @@
     answer = factorial(num)
 
     # Assert
-    expect(answer).must_equal 5*4*3*2*1
-
+    expect(answer).must_equal 5 * 4 * 3 * 2 * 1
   end
 
   it "will raise an ArgumentError if given a number not >= 0" do
@@ -38,7 +37,7 @@
   end
 end
 
-xdescribe "reverse" do
+describe "reverse" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -83,8 +82,7 @@
   end
 end
 
-
-xdescribe "reverse_in_place" do
+describe "reverse_in_place" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -129,7 +127,7 @@
   end
 end
 
-xdescribe "bunny" do
+describe "bunny" do
   it "returns 0 for 0 bunnies" do
     # Arrange
     count = 0
@@ -164,7 +162,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""
@@ -224,40 +222,40 @@
   end
 
   it "will return true when looking for something in the array" do
-  # Arrange
-  item = "a"
-  array = ["b", "c", "a"]
+    # Arrange
+    item = "a"
+    array = ["b", "c", "a"]
 
-  # Act
-  answer = search(array, item)
+    # Act
+    answer = search(array, item)
 
-  # Assert
-  expect(answer).must_equal true
+    # Assert
+    expect(answer).must_equal true
   end
 
   it "will return false when looking for something not in the array" do
     # Arrange
     item = "x"
     array = ["b", "c", "a"]
-  
+
     # Act
     answer = search(array, item)
-  
+
     # Assert
     expect(answer).must_equal false
-    end
-
-    it "will return true when finding something at the front of the array" do
-      # Arrange
-      item = "b"
-      array = ["b", "c", "a"]
-    
-      # Act
-      answer = search(array, item)
-    
-      # Assert
-      expect(answer).must_equal true
-    end      
+  end
+
+  it "will return true when finding something at the front of the array" do
+    # Arrange
+    item = "b"
+    array = ["b", "c", "a"]
+
+    # Act
+    answer = search(array, item)
+
+    # Assert
+    expect(answer).must_equal true
+  end
 end
 
 xdescribe "is_palindrome" do
@@ -304,8 +302,8 @@
     # Act
     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 4
+    # Assert
+    expect(answer).must_equal 4
   end
 
   it "returns 0 for nonmatching numbers" do
@@ -316,8 +314,8 @@
     # Act
     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 0
+    # Assert
+    expect(answer).must_equal 0
   end
 
   it "returns 3 for 841 and 62530841" do
@@ -328,7 +326,7 @@
     # Act
     answer = digit_match(num1, num2)
 
-     # Assert
-     expect(answer).must_equal 3
+    # Assert
+    expect(answer).must_equal 3
   end
-end
+end