至少蓝吧,我的数/信竞朋友推了个 a+1+(a+2k+1)+2k+1=1+2k+1(a2k+2)a+1+(a+2^{k+1})+2^{k+1}=1+2^{k+1}(\frac{a}{2^k}+2)a+1+(a+2k+1)+2k+1=1+2k+1(2ka+2),其中 lowbit(a)=2klowbit(a)=2^klowbit(a)=2k
感觉这题真的离谱,打表到底什么鬼啊,我打了,没找到啊?????
std 是什么啊???