147. 对链表进行插入排序

原题

https://leetcode.cn/problems/insertion-sort-list/description/

思路

遍历

复杂度

时间：O(n²)
空间：O(n)

Python代码

# 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 or not head.next:
            return head
        dummy = ListNode(0, head)
        while head.next:
            if head.val < head.next.val:
                head = head.next 
            else:
                prev = dummy 
                temp = head.next
                head.next = temp.next
                while prev.next and prev.next.val < temp.val:
                    prev = prev.next 
         
                temp.next = prev.next
                prev.next = temp 
        return dummy.next
            

Go代码

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func insertionSortList(head *ListNode) *ListNode {
	if head == nil || head.Next == nil {
		return head
	}
	dummy := &ListNode{0, head}
	for head.Next != nil {
		if head.Val < head.Next.Val {
			head = head.Next
		} else {
			prev := dummy
			temp := head.Next
			head.Next = temp.Next
			for prev.Next != nil && prev.Next.Val < temp.Val {
				prev = prev.Next
			}
			temp.Next = prev.Next
			prev.Next = temp
		}
	}
	return dummy.Next
}