From ea887051d30d24693ee0df7971f20a1c2ee4eb71 Mon Sep 17 00:00:00 2001
From: brilatimer <brihiramine@gmail.com>
Date: Sat, 16 Nov 2019 17:03:14 -0800
Subject: [PATCH 1/2] 3 problems complete, tests passing

---
 lib/recursive-methods.rb | 57 +++++++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 15 deletions(-)

diff --git a/lib/recursive-methods.rb b/lib/recursive-methods.rb
index fbf6faa..1d7a722 100644
--- a/lib/recursive-methods.rb
+++ b/lib/recursive-methods.rb
@@ -1,49 +1,76 @@
 # Authoring recursive algorithms. Add comments including time and space complexity for each method.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(1) because constant is being multiplied (no arrays)
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+  # solve base case 
+  if n < 0 
+    raise ArgumentError
+  end
+  if n == 0 
+    return 1 
+  end
+  if n <= 2 
+    return n 
+  end
+  return n * factorial(n-1)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n) 
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length <= 1
+    return s 
+  end
+  return [reverse(s[1, s.length - 1]), s[0]].join
 end
+# substring on the left, first char on the right, put these into an arry and call .join
+# https://apidock.com/ruby/Array/join
 
-# Time complexity: ?
-# Space complexity: ?
-def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n)
+# Space complexity: O(1), no additional space used/no new arrays/strings created
+def reverse_inplace(s, index = 0)
+  start_index = index
+  end_index = s.length - 1 - index
+  
+  # middle point has been found. this is basecase
+  if end_index <= start_index
+    return s 
+  end
+  # swap start and end elements
+  temp = s[start_index]
+  s[start_index] = s[last_index]
+  s[last_index] = temp
+  
+  return reverse_inplace(s, index + 1) # this handles swapping middle
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+  raise NotImplementedError, "Method not implemented"
 end
 
 # Time complexity: ?
 # Space complexity: ?
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
+  raise NotImplementedError, "Method not implemented"
 end
 
 # Time complexity: ?
 # Space complexity: ?
 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"
+  raise NotImplementedError, "Method not implemented"
 end
\ No newline at end of file

From 359b9a4bdc56a0cca7f37ecf75aaea783f30b2a3 Mon Sep 17 00:00:00 2001
From: brilatimer <brihiramine@gmail.com>
Date: Sun, 17 Nov 2019 15:35:30 -0800
Subject: [PATCH 2/2] nested and bunny problems working and tested

---
 lib/recursive-methods.rb       | 33 ++++++++++++++++++++++++---------
 test/recursion_writing_test.rb |  8 ++++----
 2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/lib/recursive-methods.rb b/lib/recursive-methods.rb
index 1d7a722..78146d3 100644
--- a/lib/recursive-methods.rb
+++ b/lib/recursive-methods.rb
@@ -39,22 +39,37 @@ def reverse_inplace(s, index = 0)
   end
   # swap start and end elements
   temp = s[start_index]
-  s[start_index] = s[last_index]
-  s[last_index] = temp
+  s[start_index] = s[end_index]
+  s[end_index] = temp
   
   return reverse_inplace(s, index + 1) # this handles swapping middle
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(1)
 def bunny(n)
-  raise NotImplementedError, "Method not implemented"
+  if n < 0 
+    raise ArgumentError
+  end
+  if n == 0 # basecase
+    return n
+  end
+  return bunny(n - 1) + 2
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def nested(s)
-  raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n)
+# Space complexity: O(1)
+def nested(s, index = 0) # initalize index
+  start_index = index
+  end_index = s.length - 1 - index
+  if end_index < start_index
+    return true
+  end 
+  if s[start_index] == '(' && s[end_index] == ')'
+    return nested(s, index + 1) 
+  else
+    return false
+  end
 end
 
 # Time complexity: ?
diff --git a/test/recursion_writing_test.rb b/test/recursion_writing_test.rb
index 820810e..8841792 100644
--- a/test/recursion_writing_test.rb
+++ b/test/recursion_writing_test.rb
@@ -38,7 +38,7 @@
   end
 end
 
-xdescribe "reverse" do
+describe "reverse" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -84,7 +84,7 @@
 end
 
 
-xdescribe "reverse_in_place" do
+describe "reverse_in_place" do
   it "will reverse 'cat'" do
     # Arrange
     string = "cat"
@@ -129,7 +129,7 @@
   end
 end
 
-xdescribe "bunny" do
+describe "bunny" do
   it "returns 0 for 0 bunnies" do
     # Arrange
     count = 0
@@ -164,7 +164,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""