Branches - Brianna K

lib/recursive-methods.rb

@@ -1,49 +1,103 @@
 # 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"
+  raise ArgumentError if n < 0
+  return 1 if n == 1 || n == 0
+  return n * factorial(n-1)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+
+# Time complexity: O(n/2) >> O(n)
+# Space complexity: O(n)
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length >= 2 
+    temp_char = s[0]
+    s[0] = s[-1]
+    s[-1] = temp_char
+    return s[0] + reverse(s[1...-1]) + s[-1]
+  else
+    return s
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n/2) >> O(n)
+# Space complexity: O(n)
 def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+  if s.length >= 2 
+    temp_char = s[0]
+    s[0] = s[-1]
+    s[-1] = temp_char
+    return s[0] + reverse(s[1...-1]) + s[-1]
+  else
+    return s
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+  raise ArgumentError if n < 0
+  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"
+  return true if s.length == 0
+  return false if s.length % 2 != 0
+
+  if s[0] == '(' && s[-1] == ')'
+    nested(s[1..-2])
+  else 
+    return false
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) - worst case
+# Space complexity: O(n) - worst case
 def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+  return false if array[0] == nil
+
+  return true if array[0] == value
+
+  search(array[1..-1], value)
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n/2) => O(n)
+# Space complexity: O(n/2) => O(n)
 def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+  return true if s.length <=1
+
+  if s[0] == s[-1]
+    is_palindrome(s[1..-2])
+  else 
+    return false
+  end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n) n is the length of the shortest array
+# Space complexity: O(n)
 def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
-end
+  if n.class == Integer
+    n = n.to_s.split("")   # [1, 0, 7, 2, 5, 0, 3, 8, 9, 1]
+  end
+
+  if m.class == Integer 
+    m = m.to_s.split("")   #       [6, 2, 5, 3 ,0, 8, 4, 1]
+  end
+
+  return n.length if n[-1] == nil || n[-1] == "match" 
+
+  return m.length if m[-1] == nil || m[-1] == "match"
+
+  if n[-1] == m[-1]
+    n.insert(0, "match")
+    m.insert(0, "match")
+  end
+
+  digit_match(n[0..-2], m[0..-2])
+
+end