147. Insertion Sort List

注意新的list跟原来的list是不相连的，然后把各个状态的点记录好就行：

public ListNode insertionSortList(ListNode head) {
        if (head == null || head.next == null) return head;
        
        //We started a new list here, not the original one
        ListNode dummy = new ListNode(0);
        ListNode curt = head, prev = dummy, next = head;
        while (curt != null) {
            next = curt.next;
            
            while (prev.next != null && prev.next.val < curt.val) {
                prev = prev.next;
            }
            
            curt.next = prev.next;
            prev.next = curt;
            curt = next;
            prev = dummy;
        }
        
        return dummy.next;
    }