The kind that mostly relevant to interviews, if we’re being honest.
Linked lists can be singly linked or doubly linked. Each node in a singly linked linked list has a
next property, but no
prev property. Therefore, it’s possible to walk forward but not backwards. Each node in a doubly linked linked list has a
prev property in addition to
next; it is possible to walk backwards from any node.
Strictly speaking, most operations in a linked list are constant time. Adding a node, removing a node, etc. are all constant time ASSUMING you don’t need to walk the list. Walking the list will kill you. Also, if we think about a list as a continguous chunk of memory that we’re dealing with, in the traditional sense, then we can consider different ways of accessing a node apart from walking the list.
Think of linked list operations as exclusive from walking the list.