[leetcode]Insertion Sort List

Insertion Sort List

Sort a linked list using insertion sort.

算法思路：

最基本的插入排序，时间复杂度O(n*n)，空间复杂度O(1)

代码：

public class Solution {
    public ListNode insertionSortList(ListNode head) {
        if(head == null || head.next == null) return head;
        ListNode list = new ListNode(0);
        list.next = head;
        head = head.next;
        list.next.next = null;
        while(head != null){
            ListNode tail = list;
            ListNode node = head;
            head = head.next;
            node.next = null;
            while(tail != null){
                if(tail.next == null){
                    tail.next = node;
                    break;
                }
                if(tail.next.val > node.val){
                    node.next = tail.next;
                    tail.next = node;
                    break;
                }else{
                    tail = tail.next;
                }
            }
        }
        return list.next;
    }
}