Javascript-there is an array where three integers ABC are selected, and the three integers ABC are equal to 0. how many such arrays are there?

Interview questions, please answer interview questions, please answer

Reply content:

Interview questions, please answer

Typical 3Sum, leetcode on the original question https://leetcode.com/problems...

JavaScript can look at my problem https://github.com/hanzichi/l...

This question is also the title of the introduction of old Zhao and winter handwritten questions, you can see the https://zhuanlan.zhihu.com/p...

The best method seems to be O (n ^ 2 ).

Are all determined to be 3 integers ...... Triplicate loop enumeration ............

As @ xiaoboost said, the violence against the statement can be made:

import itertoolsdef nsum(lst, n, target):    count = 0    for c in itertools.combinations(lst, n):        if sum(c) == target:            count += 1    return countif __name__ == '__main__':    lst = [-1, 3, -2, 7, -4, -3, 6, 9, -2, -2, 1, 1, 0, 10, -1, 9, 8, -12]    print(nsum(lst, 3, 0))

Result:

22

Questions I have answered: Python-QA

from itertools import combinationsdef sum_is_sth(lst, sth=0, cnt=3):    return sum([1 for sub_lst in combinations(lst, cnt) if sum(sub_lst) == sth])