leetcode/solution/0100-0199/0148.Sort List/Solution.cs

42 lines
1.1 KiB
C#

/**
* Definition for singly-linked list.
* public class ListNode {
* public int val;
* public ListNode next;
* public ListNode(int val=0, ListNode next=null) {
* this.val = val;
* this.next = next;
* }
* }
*/
public class Solution {
public ListNode SortList(ListNode head) {
if (head == null || head.next == null) {
return head;
}
ListNode slow = head, fast = head.next;
while (fast != null && fast.next != null) {
slow = slow.next;
fast = fast.next.next;
}
ListNode l1 = head, l2 = slow.next;
slow.next = null;
l1 = SortList(l1);
l2 = SortList(l2);
ListNode dummy = new ListNode();
ListNode tail = dummy;
while (l1 != null && l2 != null) {
if (l1.val <= l2.val) {
tail.next = l1;
l1 = l1.next;
} else {
tail.next = l2;
l2 = l2.next;
}
tail = tail.next;
}
tail.next = l1 != null ? l1 : l2;
return dummy.next;
}
}