From 6b925f9dd445c81ead007d8d17ce6098eac85aea Mon Sep 17 00:00:00 2001
From: Janice Lichtman <jalichtman@gmail.com>
Date: Tue, 28 Mar 2017 07:57:11 -0700
Subject: [PATCH 1/3] wrote methods for #1-3

---
 README.md            |  1 +
 recursive-methods.rb | 81 ++++++++++++++++++++++++++++++++------------
 sandbox.rb           | 12 +++++++
 3 files changed, 72 insertions(+), 22 deletions(-)
 create mode 100644 sandbox.rb

diff --git a/README.md b/README.md
index dd66f4c..5d066eb 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,7 @@ Write a method `factorial` that accepts an integer parameter n and that uses rec
 
 - e.g. fact(4) = 4 * 3 * 2 * 1 = 24
 
+
 ### Write #2
 `reverse(s)`
 Write a method `reverse` that accepts a string as a parameter
diff --git a/recursive-methods.rb b/recursive-methods.rb
index 7daaac0..92d700e 100644
--- a/recursive-methods.rb
+++ b/recursive-methods.rb
@@ -1,34 +1,71 @@
 
 def factorial(n)
+  raise ArgumentError.new("Not an integer") if
+  !(n.class==Integer)
+  raise ArgumentError.new("Not a positive integer") if n < 0
+  if n==0
+    return 1
+  else
+    return n * factorial(n-1)
+  end
 end
 
-def reverse(s)
-end
 
-def bunny(n)
-end
+#with tail recursion (just for fun):
+def factorialB(n, total=1)
+  raise ArgumentError.new("Not an integer") if
+  !(n.class==Integer)
+  raise ArgumentError.new("Not a positive integer") if n < 0
 
-def nested(s)
+  if n==0
+    return total
+  else
+    return factorialB(n-1, n * total)
+  end
 end
 
-# Factorial Tests
-raise "factorial broke - factorial(4)" unless factorial(4) == 24
-raise "factorial broke - factorial(0)" unless factorial(0) == 1
-puts "passes all factorial tests"
 
-# Reverse Tests
-raise "reverse broke - reverse('hello world')" unless reverse("hello world") == "dlrow olleh"
-raise "reverse broke - reverse('a b c')" unless reverse("a b c") == "c b a"
-puts "passes all reverse tests"
+def reverse(s)
+  if s.nil? || s.length==0
+    return ""
+  else
+    return reverse(s[1..-1])+s[0]
+  end
+end
 
-# Bunny Tests
-raise "bunny broke - bunny(0)" unless bunny(0) == 0
-raise "bunny broke - bunny(10)" unless bunny(10) == 20
-puts "passes all bunny tests"
+def bunny(n)
+  raise ArgumentError.new("Not an integer") if
+  !(n.class==Integer)
+  raise ArgumentError.new("Not a positive integer") if n < 0
 
-# Nested Tests
-raise "nested broke - nested('((()))')" unless reverse("((()))") == true
-raise "nested broke - nested('())')" unless reverse("())") == false
-puts "passes all nested tests"
+  if n==0
+    return 0
+  else
+    return bunny(n-1) + 2
+  end
+end
 
-puts "All test passed"
+# def nested(s)
+# end
+#
+# # Factorial Tests
+# raise "factorial broke - factorial(4)" unless factorial(4) == 24
+# raise "factorial broke - factorial(0)" unless factorial(0) == 1
+# puts "passes all factorial tests"
+#
+# # Reverse Tests
+# raise "reverse broke - reverse('hello world')" unless reverse("hello world") == "dlrow olleh"
+# raise "reverse broke - reverse('a b c')" unless reverse("a b c") == "c b a"
+# puts "passes all reverse tests"
+#
+# # Bunny Tests
+# raise "bunny broke - bunny(0)" unless bunny(0) == 0
+# raise "bunny broke - bunny(10)" unless bunny(10) == 20
+# puts "passes all bunny tests"
+#
+# # Nested Tests
+# raise "nested broke - nested('((()))')" unless reverse("((()))") == true
+# raise "nested broke - nested('())')" unless reverse("())") == false
+# puts "passes all nested tests"
+#
+# puts "All test passed"
diff --git a/sandbox.rb b/sandbox.rb
new file mode 100644
index 0000000..d6849e4
--- /dev/null
+++ b/sandbox.rb
@@ -0,0 +1,12 @@
+
+def factorial(n)
+  raise ArgumentError.new("Not an integer") if
+  !(n.class==Integer)
+  raise ArgumentError.new("Not a positive integer") if n < 0
+
+ if n==0
+   return 1
+ else
+   return n * factorial(n-1)
+ end
+end

From d0b93b524232fdfdafe6eb043ba02a35ae0296df Mon Sep 17 00:00:00 2001
From: Janice Lichtman <jalichtman@gmail.com>
Date: Tue, 28 Mar 2017 22:27:58 -0700
Subject: [PATCH 2/3] wrote methods for palindromes and fibonacci

---
 recursive-methods.rb | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/recursive-methods.rb b/recursive-methods.rb
index 92d700e..ae8e098 100644
--- a/recursive-methods.rb
+++ b/recursive-methods.rb
@@ -2,7 +2,7 @@
 def factorial(n)
   raise ArgumentError.new("Not an integer") if
   !(n.class==Integer)
-  raise ArgumentError.new("Not a positive integer") if n < 0
+  raise ArgumentError.new("Not a non-negative integer") if n < 0
   if n==0
     return 1
   else
@@ -15,7 +15,7 @@ def factorial(n)
 def factorialB(n, total=1)
   raise ArgumentError.new("Not an integer") if
   !(n.class==Integer)
-  raise ArgumentError.new("Not a positive integer") if n < 0
+  raise ArgumentError.new("Not a non-negative integer") if n < 0
 
   if n==0
     return total
@@ -36,8 +36,7 @@ def reverse(s)
 def bunny(n)
   raise ArgumentError.new("Not an integer") if
   !(n.class==Integer)
-  raise ArgumentError.new("Not a positive integer") if n < 0
-
+  raise ArgumentError.new("Not a non-negative integer") if n < 0
   if n==0
     return 0
   else
@@ -48,6 +47,35 @@ def bunny(n)
 # def nested(s)
 # end
 #
+
+def fib(n)
+  raise ArgumentError.new("Not an integer") if
+  !(n.class==Integer)
+  raise ArgumentError.new("Not a positive integer") if n < 0
+  if n == 1
+    return 1
+  elsif n == 2
+    return 1
+  else
+    return fib(n-1) + fib(n-2)
+  end
+end
+
+def pal(s)
+  if (s.length == 1) || (s.length == 0)
+    return true
+  elsif s[0] == s[-1]
+   return pal(s[1..-2])
+  else
+    return false
+  end
+end
+
+
+
+
+
+
 # # Factorial Tests
 # raise "factorial broke - factorial(4)" unless factorial(4) == 24
 # raise "factorial broke - factorial(0)" unless factorial(0) == 1

From 6440a489e27b8a746ff8f22081a4b6f24e5a7dee Mon Sep 17 00:00:00 2001
From: Janice Lichtman <jalichtman@gmail.com>
Date: Wed, 29 Mar 2017 00:07:10 -0700
Subject: [PATCH 3/3] solved all problems

---
 recursive-methods.rb | 89 +++++++++++++++++++++++++++++++++-----------
 sandbox.rb           | 29 ++++++++++-----
 2 files changed, 88 insertions(+), 30 deletions(-)

diff --git a/recursive-methods.rb b/recursive-methods.rb
index ae8e098..46f62b7 100644
--- a/recursive-methods.rb
+++ b/recursive-methods.rb
@@ -33,6 +33,7 @@ def reverse(s)
   end
 end
 
+
 def bunny(n)
   raise ArgumentError.new("Not an integer") if
   !(n.class==Integer)
@@ -44,9 +45,54 @@ def bunny(n)
   end
 end
 
-# def nested(s)
-# end
-#
+
+#Accepts ()() as acceptable 'nestings' of parentheses.
+def nested(s,  counter = 0)
+  s.each_char do |paren|
+    raise ArgumentError.new("Includes non-paren characters") if !['(',')'].include?(paren)
+  end
+
+  if s.length == 0
+    (counter == 0)? true:false
+  elsif s[0]=='('
+    counter += 1
+    return nested(s[1..-1], counter)
+  elsif s[0]==')'
+    counter -= 1
+    if counter < 0
+      return false
+    else
+      return nested(s[1..-1], counter)
+    end
+  end
+end
+
+
+# Only accepts strictly nested strings of parenteses.
+# Ex ()() will count as false.
+def strictly_nested(s,  counter = 0)
+  s.each_char do |paren|
+    raise ArgumentError.new("Includes non-paren characters") if !['(',')'].include?(paren)
+  end
+
+  if s.length == 0
+    (counter == 0)? true:false
+  elsif s[0]=='('
+    counter += 1
+    return strictly_nested(s[1..-1], counter)
+  elsif s[0]==')'
+    counter -= 1
+    #Since we only want strictly nested parentheses [ie don't want to allow ()() ], if counter hits 0 and there are more characters in the string, the method should return false.
+    if counter == 0 && s.length != 1
+      return false
+    else
+      return strictly_nested(s[1..-1], counter)
+    end
+  end
+end
+
+
+####### Added Fun
 
 def fib(n)
   raise ArgumentError.new("Not an integer") if
@@ -61,11 +107,12 @@ def fib(n)
   end
 end
 
+
 def pal(s)
   if (s.length == 1) || (s.length == 0)
     return true
   elsif s[0] == s[-1]
-   return pal(s[1..-2])
+    return pal(s[1..-2])
   else
     return false
   end
@@ -73,27 +120,27 @@ def pal(s)
 
 
 
+# Factorial Tests
+raise "factorial broke - factorial(4)" unless factorial(4) == 24
+raise "factorial broke - factorial(0)" unless factorial(0) == 1
+puts "passes all factorial tests"
 
+# Reverse Tests
+raise "reverse broke - reverse('hello world')" unless reverse("hello world") == "dlrow olleh"
+raise "reverse broke - reverse('a b c')" unless reverse("a b c") == "c b a"
+puts "passes all reverse tests"
 
+# Bunny Tests
+raise "bunny broke - bunny(0)" unless bunny(0) == 0
+raise "bunny broke - bunny(10)" unless bunny(10) == 20
+puts "passes all bunny tests"
 
-# # Factorial Tests
-# raise "factorial broke - factorial(4)" unless factorial(4) == 24
-# raise "factorial broke - factorial(0)" unless factorial(0) == 1
-# puts "passes all factorial tests"
-#
-# # Reverse Tests
-# raise "reverse broke - reverse('hello world')" unless reverse("hello world") == "dlrow olleh"
-# raise "reverse broke - reverse('a b c')" unless reverse("a b c") == "c b a"
-# puts "passes all reverse tests"
-#
-# # Bunny Tests
-# raise "bunny broke - bunny(0)" unless bunny(0) == 0
-# raise "bunny broke - bunny(10)" unless bunny(10) == 20
-# puts "passes all bunny tests"
-#
 # # Nested Tests
 # raise "nested broke - nested('((()))')" unless reverse("((()))") == true
 # raise "nested broke - nested('())')" unless reverse("())") == false
 # puts "passes all nested tests"
-#
-# puts "All test passed"
+
+puts 'typo in the nested tests. written as reverse instead of nested'
+
+
+puts "All test passed"
diff --git a/sandbox.rb b/sandbox.rb
index d6849e4..12c247d 100644
--- a/sandbox.rb
+++ b/sandbox.rb
@@ -1,12 +1,23 @@
+# Only accepts strictly nested strings of parenteses.
+# Ex ()() will count as false.
 
-def factorial(n)
-  raise ArgumentError.new("Not an integer") if
-  !(n.class==Integer)
-  raise ArgumentError.new("Not a positive integer") if n < 0
+def strictly_nested(s,  counter = 0)
+  s.each_char do |paren|
+    raise ArgumentError.new("Includes non-paren characters") if !['(',')'].include?(paren)
+  end
 
- if n==0
-   return 1
- else
-   return n * factorial(n-1)
- end
+  if s.length == 0
+    (counter == 0)? true:false
+  elsif s[0]=='('
+    counter += 1
+    return strictly_nested(s[1..-1], counter)
+  elsif s[0]==')'
+    counter -= 1
+    #Since we only want strictly nested parentheses [ie don't want to allow ()() ], if counter hits 0 and there are more characters in the string, the method should return false.
+    if counter == 0 && s.length != 1
+      return false
+    else
+      return strictly_nested(s[1..-1], counter)
+    end
+  end
 end