148. 排序链表

原题

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

思路

转为列表后排序

复杂度

时间：O(n * log(n))
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 sortList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        if not head:
            return None 
        l = []
        while head:
            l.append(head.val)
            head = head.next 
        l.sort()
        dummy = cur = ListNode(-1)
        for val in l:
            cur.next = ListNode(val)
            cur = cur.next 
        return dummy.next
        

Go代码

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func sortList(head *ListNode) *ListNode {
	if head == nil {
		return head
	}
	l := []int{}
	for head != nil {
		l = append(l, head.Val)
		head = head.Next
	}
	sort.Ints(l)
	dummy := &ListNode{}
	cur := dummy
	for _, val := range l {
		cur.Next = &ListNode{Val: val}
		cur = cur.Next
	}
	return dummy.Next
}