摘要：
A digit sum S_b(n)Sb(n) is a sum of the base-bb digits of nn. Such as S_{10}(233) = 2 + 3 + 3 = 8S10(233)=2+3+3=8, S_{2}(8)=1 + 0 + 0 = 1S2(8)=1+0+ 阅读全文
摘要：
There are NN light bulbs indexed from 00 to N-1N−1. Initially, all of them are off. A FLIP operation switches the state of a contiguous subset of bulb 阅读全文