题目浅析

  • 想查看原题可以点击题目链接

  • 简单地说,就是给一个链表,要对这个链表做插入排序。

思路分享

代码解答(强烈建议自行解答后再看)

  • 参考题解
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# Definition for singly-linked list.
# class ListNode:
# def __init__(self, val=0, next=None):
# self.val = val
# self.next = next
class Solution:
def insertionSortList(self, head: Optional[ListNode]) -> Optional[ListNode]:
if not head:
return head

sentinal = ListNode(0, head)
cur = head
last_sorted = head
while cur.next:
cur = cur.next
if cur.val < last_sorted.val:
pre = sentinal
while pre.next.val < cur.val:
pre = pre.next
last_sorted.next = cur.next
insert_next = pre.next
pre.next = cur
cur.next = insert_next
else:
last_sorted = last_sorted.next
cur = last_sorted

return sentinal.next