Water - Kayla Johnson

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 +1,85 @@
 # Authoring recursive algorithms. Add comments including time and space complexity for each method.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) ['n' being the number of times factorial computation has to be implemented until n reaches 0]
+# Space complexity: 0(n) ['n' being the number of function calls on the stack]
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+    raise ArgumentError if n < 0
+    return 1 if n == 0
+    return n * factorial(n - 1)
+
+end
+
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
+def reverse(s, i = 1)
+    return s if s == "" || s.length < 2
+    reversed = reverse(s[1..-1])
+    reversed += s[0]
+    return reversed
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n) -still has to iterate over every element in string
+# Space complexity: O(n) -stack can get very large if string is big
+def reverse_inplace_helper(s, start, finish)
+    if start < finish
+        s[start], s[finish] = s[finish], s[start]
+        return reverse_inplace_helper(s, start + 1, finish - 1)
+    else
+        return s
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+    return reverse_inplace_helper(s, 0, s.length - 1)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# Time complexity: O(n)
+# Space complexity: O(n)
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+    return 0 if n <= 0
+    return 2 + bunny(n - 1)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def nested(s)
-    raise NotImplementedError, "Method not implemented"
-end
+    return true if s == "" || s.length == 0
+    return false if s.length.odd?
+    while s[0] == '(' && s[-1] == ')'
+        return nested(s[1..-2])
+    end
+        return false
+    end
+
+# Time complexity: O(n) best case O(1) if item is in index 1?
+# Space complexity: O(n) best case O(1) if item is in index 1?
+def search(array, value, i = 0)
+    return true if array[i] == value
+    return false if i >= array.length
+    return search(array, value, i + 1)
 
-# Time complexity: ?
-# Space complexity: ?
-def search(array, value)
-    raise NotImplementedError, "Method not implemented"
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) - traversing the whole string
+# Space complexity: O(n) -traversing the whole string
 def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+    return true if s == "" || s.length < 2
+    return false if s[0] != s[-1]
+        return is_palindrome(s[1..-2])
+end
+
+# Time complexity: O(n)
+# Space complexity: O(n)
+def digit_helper(n, m, match = 0, place = 0)
+    return 1 if n == 0 && m == 0 && place == 0
+    return match if n == 0 || m == 0
+    match += 1 if n % 10 == m % 10
+    return digit_helper(n/10, m/10, match, place + 1)
+    return match
 end
 
-# Time complexity: ?
-# Space complexity: ?
 def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
-end
+    return digit_helper(n, m, 0,  0)
+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