A doubly linked list yana ba da kowane node biyu pointers — next da prev — don kad za ka iya yin traverse a bankamaɗi-bankamaɗi da kuma kasa node a cikin O(1) lokacin da kake rike abin ambatanci ga shi (babu buƙatun yin tafiya daga gida don nemo masu jiya).
null <- [10] <-> [20] <-> [30] -> null
prev/next links in BOTH directions
class Node:
def __init__(self, val):
self.val, self.prev, self.next = val, None, None
def remove(node): # O(1) — no traversal needed
if node.prev: node.prev.next = node.next
if node.next: node.next.prev = node.prev
A cikin singly linked list, kasawa node yana buƙatar nemo masu jiya a farko → O(n).
| Allon | Singly | Doubly |
|---|---|---|
| Pointers a cikin node | 1 (next) | 2 (next, prev) |
| Traverse baya | a'a | eh |
| Kasa node da aka sani | O(n) | O(1) |
| Waje memory | karami | girma |
O(1) splice-out na node da aka sani shine abin mahimmanwacin da ya sa doubly linked lists su zama aboki na hash maps a cikin LRU cache.
Extra prev pointer yana jiye memory don sako ta motsi na bankamaɗi-bankamaɗi da kuma kasawa a lokaci mai daidai.