>>> x = [[1,4],[5,2]]
>>> x [[1, 4], [5, 2]]
>>> x.sort()
>>> x [[1, 4], [5, 2]]
>>> def g(u,v):
... return u[1]-v[1]
...
>>> x.sort(g)
>>> x [[5, 2], [1, 4]]
从def开始就不明白了,请说明,谢谢。
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