📅  最后修改于: 2023-12-03 14:53:57.418000             🧑  作者: Mango
展平链表是一种常见的问题,特别在处理多层嵌套的链表结构时。套装2提供了一些优化和扩展,以解决不同类型的展平链表问题。
以下是一些解决展平链表问题的常用方法:
递归法是一种常用的解决方法。它通过递归地处理链表的每个节点,逐步将链表展平为单层链表。
def flatten_linked_list(head):
# Base case
if not head:
return None
# Flatten the next level recursively
flattened_next = flatten_linked_list(head.next)
# Flatten the child level recursively
flattened_child = flatten_linked_list(head.child)
# Connect the child and next layers
if flattened_child:
tail = flattened_child
while tail.next:
tail = tail.next
tail.next = flattened_next
if flattened_next:
flattened_next.prev = tail
# Connect the current layer and child
head.next = flattened_child
if flattened_child:
flattened_child.prev = head
head.child = None
return head
迭代法通过使用栈来模拟递归的过程。它遍历链表,将有child的节点放入栈中,并将child置为空。然后从栈中逐个取出节点,并将取出的节点的next设置为栈中的下一个节点。
def flatten_linked_list(head):
if not head:
return None
stack = []
current = head
while current:
if current.child:
if current.next:
stack.append(current.next)
current.next = current.child
current.next.prev = current
current.child = None
elif not current.next and stack:
next_node = stack.pop()
current.next = next_node
next_node.prev = current
current = current.next
return head
套装2还解决了一些扩展问题,例如:
# 示例:展平直到第K层,保持原始链表结构
def flatten_linked_list_till_k(head, k):
if not head:
return None
current = head
level = 1
while current:
if level == k and current.child:
flattened_child = flatten_linked_list_till_k(current.child, k)
next_node = current.next
current.next = flattened_child
flattened_child.prev = current
current.child = None
while current.next:
current = current.next
current.next = next_node
if next_node:
next_node.prev = current
else:
current = current.next
if not current:
break
if not current.next and current.child:
level += 1
current = current.child
return head
通过使用套装2提供的解决方案,程序员们可以轻松地解决各种展平链表问题。递归和迭代是最常用的方法,而套装2还提供了处理链表中循环和特定深度要求的功能。使用这些方法,程序员们能够高效地解决展平链表问题,提高代码质量和效率。