冒泡排序思想,超时

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

#
# 
# @param head ListNode类 the head node
# @return ListNode类
#
class Solution:
    def sortInList(self , head ):
        # write code here
        # 冒泡排序
        length = 0
        p = head
        while p:
            length += 1
            p = p.next
        for _ in range(length):
            pre = head 
            while pre and pre.next:
                cur = pre.next
                if pre.val > cur.val:
                    pre.val, cur.val = cur.val, pre.val
                pre = pre.next
        return head