Dragonfly - Tatyana A.

part-1.py

@@ -4,17 +4,48 @@
 # the appropriate comment.
 
 # factorial
+def factorial(n):
+    if n < 0:
+        raise ValueError
+    if n == 0:
+        return 1
+
+    return n * factorial(n-1)
 
 
 
 # reverse
+def reverse(text):
+    if len(text) <= 1:
+        return text
+
+    return reverse(text[1:]) + text[0]
 
 
 
 # bunny
+def bunny(count):
+    if count == 0:
+        return 0
+
+    return 2 + bunny(count-1)
 
 
 
-# is_nested_parens
+# is_nested_parensdef is_nested_parens(parens):
+def is_nested_parens(parens):
+    return is_nested_helper(parens, 0)
 
 
+
+def is_nested_helper(parens, count):
+    if not parens:
+        return count == 0  
+
+    if parens[0] == '(':
+        return is_nested_helper(parens[1:], count + 1)
+    elif parens[0] == ')':
+        if count == 0:
+            return False  
+        return is_nested_helper(parens[1:], count - 1)
+    return False 

part-2.py

@@ -4,13 +4,44 @@
 # the appropriate comment.
 
 # search
+def search(array, query):
+    if not array:
+        return False
+
+    if array[0] == query:
+        return True
+
+    return search(array[1:], query)
 
 
 
 # is_palindrome
+def is_palindrome(s_input):
+    if len(s_input) <= 1:
+        return True
+
+    if s_input[0] != s_input[-1]:
+        return False
+
+    return is_palindrome(s_input[1:-1])
 
 
 
 # digit_match
-
+def digit_match(number1, number2): 
+    if number1 == 0 and number2 == 0:
+        return 1
+
+    elif number1 < 10 or number2 < 10:
+        count_pairs = 0
+        if number1 % 10 == number2 % 10:
+            count_pairs += 1
+        return count_pairs
+
+
+    count_pairs = 0
+    if number1 % 10 == number2 % 10:
+        count_pairs += 1
+
+    return count_pairs + digit_match(number1 // 10, number2 // 10)