Python:TypeError:"NoneType"对象不可下标 [英] Python: TypeError: 'NoneType' object is not subscriptable

问题描述

#Uses python3

import sys

def max_dot_product(a,b,n):


    a = a.sort(reverse=True)
    b = b.sort(reverse=True)
    res = 0

    for i in range(n):
        res += a[i]*b[i]
    return res

if __name__ == '__main__':
    data = [int(x) for x in input("").split()]
    n = data[0]
    a = data[1:(n + 1)]
    b = data[(n + 1):]
    print(max_dot_product(a,b,n))

当我运行此代码时，它表明"TypeError:'NoneType'对象不可下标".

When I run this code, it reveals that "TypeError: 'NoneType' object is not subscriptable".

推荐答案

sort对列表进行排序，并(隐式)返回None.删除返回值的分配，您应该可以:

sort sorts a list in place and (implicitly) returns None. Drop the assignment of the return value and you should be OK:

a.sort(reverse=True)
b.sort(reverse=True)

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