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Second analytical, with exact integer math only solution in Clear category for Can Balance by juestr
from itertools import starmap
from operator import mul
from typing import Iterable
def can_balance(weights: Iterable) -> int:
# torque == sum((i - p) * w for i, w in enumerate(weights)) == 0
# ==> sum(i*w_i) - sum(p*w_i) == 0
# ==> sum(i*w_i) - p*sum(w_i) == 0
# ==> p == sum(i*w_i)/sum(w_i)
position, notexact = divmod(sum(starmap(mul, enumerate(weights))), sum(weights))
return -1 if notexact else position
April 22, 2019
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