不排序找出前2个最大值

In [90]: lst = [1,2,3,6,3,4,5,4]
    ...:
    ...: max = -9999
    ...: secMax = -99999
    ...: for x in lst:
    ...:
    ...:     if x > max:
    ...:         max = x
    ...:     if x > secMax and x < max:
    ...:         secMax = x
    ...:

In [91]: print(max)
6

In [92]: print(secMax)
5