implements the print method

04_linkedList/ll.py

@@ -12,7 +12,7 @@ class SingleListItem():
     """		
     def __init__(self, value, nexti=None):
         self.value = value
-        self.nexti = nexti
+        self.nexti = nexti # pointer of the next element in the list
 
     def has_next(self):
 		"""
@@ -25,10 +25,49 @@ class SingleLinkedList():
 	Linked list with only one link between items.
 	The list can only be traversed one way"""
 	
-	def __init__():
-		self.root= SinglelistItem(None, None) # The head
+	def __init__(self):
+		self._size = 0
+		self._root = None # reference of the head
+
+	def add(self, value):
+		"""
+		Adds a new element to the end of the list
+		"""
+		if self._root is None:
+			# empty tree
+			self._root = SingleListItem(value)
+		else:
+			curr = self._root
+			while(curr.nexti is not None):
+				#gets last item
+				curr = curr.nexti
+
+			item = SingleListItem(value)
+			curr.nexti = item
+			
+		self._size += 1
+		
+	def __len__(self):
+		# Returns the number of elements in the list
+		return self._size
+			
+	def __str__(self):
+		"""
+		Prints out all values in the list
+		"""
+		to_print = ""
+		curr = self._root
+		to_print += str(curr.value) 
+		while(curr.nexti is not None):
+			curr = curr.nexti
+			to_print += ", " + str(curr.value)
+
+		return to_print
 
 if __name__ == "__main__":
-	a = 12
-	t = SingleListItem(12)
-	print t.has_next()
+	ll = SingleLinkedList()
+	ll.add(3)
+	ll.add(4)
+	ll.add(5)
+	ll.add(6)
+	print ll