change reverse sll to require recursion

Author: briandoyle81

reverse/reverse.py

@@ -1,47 +1,50 @@
 class Node:
-  def __init__(self, value=None, next_node=None):
-    # the value at this linked list node
-    self.value = value
-    # reference to the next node in the list
-    self.next_node = next_node
+    def __init__(self, value=None, next_node=None):
+        # the value at this linked list node
+        self.value = value
+        # reference to the next node in the list
+        self.next_node = next_node
 
-  def get_value(self):
-    return self.value
+    def get_value(self):
+        return self.value
 
-  def get_next(self):
-    return self.next_node
+    def get_next(self):
+        return self.next_node
+
+    def set_next(self, new_next):
+        # set this node's next_node reference to the passed in node
+        self.next_node = new_next
 
-  def set_next(self, new_next):
-    # set this node's next_node reference to the passed in node
-    self.next_node = new_next
 
 class LinkedList:
-  def __init__(self):
-    # reference to the head of the list
-    self.head = None
-
-  def add_to_head(self, value):
-    node = Node(value)
-    if self.head is not None:
-      node.set_next(self.head)
-    
-    self.head = node
-
-  def contains(self, value):
-    if not self.head:
-      return False
-    # get a reference to the node we're currently at; update this as we traverse the list
-    current = self.head
-    # check to see if we're at a valid node 
-    while current:
-      # return True if the current value we're looking at matches our target value
-      if current.get_value() == value:
-        return True
-      # update our current node to the current node's next node
-      current = current.get_next()
-    # if we've gotten here, then the target node isn't in our list
-    return False
-
-  def reverse_list(self):
-    # TO BE COMPLETED
-    pass
+    def __init__(self):
+        # reference to the head of the list
+        self.head = None
+
+    def add_to_head(self, value):
+        node = Node(value)
+        if self.head is not None:
+            node.set_next(self.head)
+
+        self.head = node
+
+    def contains(self, value):
+        if not self.head:
+            return False
+        # get a reference to the node we're currently at; update this as we
+        # traverse the list
+        current = self.head
+        # check to see if we're at a valid node
+        while current:
+            # return True if the current value we're looking at matches our
+            # target value
+            if current.get_value() == value:
+                return True
+            # update our current node to the current node's next node
+            current = current.get_next()
+        # if we've gotten here, then the target node isn't in our list
+        return False
+
+    def reverse_list(self, node, prev):
+        # You must use recursion for this solution
+        pass

reverse/test_reverse.py

@@ -20,12 +20,12 @@ def test_contains(self):
     self.assertFalse(self.list.contains(1000))
 
   def test_empty_reverse(self):
-    self.list.reverse_list()
+    self.list.reverse_list(self.list.head, None)
     self.assertEqual(self.list.head, None)
 
   def test_single_reverse(self):
     self.list.add_to_head(1)
-    self.list.reverse_list()
+    self.list.reverse_list(self.list.head, None)
     self.assertEqual(self.list.head.value, 1)
 
   def test_longer_reverse(self):
@@ -35,7 +35,7 @@ def test_longer_reverse(self):
     self.list.add_to_head(4)
     self.list.add_to_head(5)
     self.assertEqual(self.list.head.value, 5)
-    self.list.reverse_list()
+    self.list.reverse_list(self.list.head, None)
     self.assertEqual(self.list.head.value, 1)
     self.assertEqual(self.list.head.get_next().value, 2)
     self.assertEqual(self.list.head.get_next().get_next().value, 3)