diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index e69de29..9fcefaf 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -0,0 +1,57 @@ +# A single node in the list +class ListNode: + def __init__(self, value): + self.value = value + self.previous = None + self.next = None +# The linked list class +class LinkedList: + def __init__(self): + self.head = None + self.tail = None + + # Add a value to the front of the list + def push_head(self, value): + new_node = ListNode(value) + new_node.next = self.head + + if self.head: + self.head.previous = new_node + + self.head = new_node + + if self.tail is None: + self.tail = new_node + + return new_node + + # Remove and return value from the end + def pop_tail(self): + if self.tail is None: + return None + + value = self.tail.value + + if self.tail.previous: + self.tail = self.tail.previous + self.tail.next = None + else: + self.head = None + self.tail = None + + return value + + # Remove a node from the list + def remove(self, node): + if node.previous: + node.previous.next = node.next + else: + self.head = node.next + + if node.next: + node.next.previous = node.previous + else: + self.tail = node.previous + + node.previous = None + node.next = None \ No newline at end of file