Earth - Emily

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 (5.14.2)
+    minitest-reporters (1.4.2)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    minitest-skip (0.0.3)
+      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 +1,112 @@
 # Authoring recursive algorithms. Add comments including time and space complexity for each method.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n), where n is the length
+# Space complexity: O(n), uses up some space in the call stack until it reaches the base case
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+    if n == 0
+        return 1
+    elsif n <= 0
+        raise ArgumentError
+    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
+    end
+
+    return s[-1] + reverse(s[1..-2]) + s[0]
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+    first = 0
+    last = s.length - 1
+    return reverse_inplace_helper(s, first, last)
+end
+
+def reverse_inplace_helper(s, first = 0, last = s.length - 1)
+    if first > last
+        return s
+    end
+
+    temp = s[first]
+    s[first] = s[last]
+    s[last] = temp
+
+    return reverse_inplace_helper(s, first + 1, last - 1)
 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
+    end
+
+    return 2 + bunny(n-1)
 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.length < 1
+        return true
+    elsif  s == "(" || s == ")"
+        return false
+    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[0]
+        return true
+    else
+        return search(array[1..-1], value)
+    end
 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 < 1
+        return true
+    elsif s[0] != s[-1]
+        return false
+    else
+        return is_palindrome(s[1..-2])
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)?
+# Space complexity: O(n^2)?
 def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
+    n = n.to_s
+    m = m.to_s
+
+    count = 0
+    return digit_match_counter(n, m, count)
+end
+
+def digit_match_counter(n, m, count)
+    if n.length == 0 || m.length == 0
+        return count
+    elsif n[-1] == m[-1]
+        count += 1
+    end
+
+    return digit_match_counter(n[0..-2], m[0..-2], count)
 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