public static void main(String[] args) {
        Solution solution = new Solution();
        
        List<ListNode> testCase = getTestCase();
        
        long start = System.currentTimeMillis();
        
        for (ListNode tc : testCase) {
            tc.printList();
            ListNode ln = solution.sortList(tc);
            ln.printList();
        }
        
        long end = System.currentTimeMillis();
        
        System.out.printf("time cost: %dms", end - start);
    }