Earth - Beauttie

Gemfile.lock

@@ -0,0 +1,36 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ansi (1.5.0)
+    builder (3.2.4)
+    coderay (1.1.3)
+    method_source (1.0.0)
+    minitest (5.14.1)
+    minitest-reporters (1.4.2)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    minitest-skip (0.0.1)
+      minitest (~> 5.0)
+    minitest-spec (0.0.2.1)
+      minitest (>= 3.0)
+    pry (0.13.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    rake (13.0.1)
+    ruby-progressbar (1.10.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  minitest
+  minitest-reporters
+  minitest-skip
+  minitest-spec
+  pry
+  rake
+
+BUNDLED WITH
+   2.1.4

lib/recursive-methods.rb

@@ -1,49 +1,110 @@
 # 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
+        raise ArgumentError
+    elsif n == 0
+        return 1
+    else
+        return n * factorial(n - 1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
 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: ?
-def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n)
+# Space complexity: O(n)
+def reverse_inplace(s, first = 0, last = s.length - 1)
+    if last <= first
+        return s
+    else
+        s[first], s[last] = s[last], s[first]
+        return reverse_inplace(s, first + 1, last - 1)
+    end
 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
+    elsif n == 1
+        return 2
+    else
+        return 2 + bunny(n - 1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
+    if s.empty?
+        return true
+    elsif s[0] == "(" && s[-1] == ")"
+        return nested(s[1..-2])
+    else
+        return false
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
 def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+    if array.empty?
+        return false
+    elsif value == array.first
+        return true
+    else
+        return search(array[1..-1], value)
+    end
 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, first = 0, last = s.length - 1)
+    if last <= first
+        return true
+    elsif s[first] != s[last]
+        return false
+    else
+        return is_palindrome(s, first + 1, last - 1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(log n)
+# Space complexity: O(log n)
+def digit_match(n, m, num_matches = 0)
+    raise ArgumentError if n < 0 || m < 0
+
+    num_matches += 1 if n % 10 == m % 10
+
+    if n < 10 || m < 10
+        return num_matches
+    else
+        return digit_match(n/10, m/10, num_matches)
+    end
+end
+
+# Time complexity: O(2^n); each fib makes two recursive calls
+# Space complexity: O(2^n)
+def fib(n)
+    raise ArgumentError if n < 0
+
+    if n == 0
+        return 0
+    elsif n == 1
+        return 1
+    else
+        return fib(n - 1) + fib(n - 2)
+    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
@@ -359,3 +359,50 @@
     expect(answer).must_equal 1
   end
 end
+
+describe "fib" do
+  it "will return 0 as the first Fibonacci number" do
+    # Arrange
+    n = 0
+
+    # Act
+    answer = fib(n)
+
+    # Assert
+    expect(answer).must_equal 0
+  end
+
+  it "will return 1 as the second Fibonacci number" do
+    # Arrange
+    n = 1
+
+    # Act
+    answer = fib(n)
+
+    # Assert
+    expect(answer).must_equal 1
+
+  end
+
+  it "return the nth Fibonacci number" do
+    # Arrange
+    n = 4
+
+    # Act
+    answer = fib(n)
+
+    # Assert
+    expect(answer).must_equal 3
+
+  end
+
+  it "will raise an ArgumentError if given a number not >= 0" do
+    # Arrange
+    n = -1
+
+    # Act-Assert
+    expect {
+      fib(n)
+    }.must_raise ArgumentError
+  end
+end