Solution -「BZOJ 3771」Triple
DescriptionLink.给你一个序列,你每次可以取 $1\sim3$ 个数然后计算和,问你对于每一种和,方案数是多少。Solution设一个 OGF $A(x)=\sum_{i=0}^{...
In mathematics you don't understand things, you just get used to them.
In mathematics you don't understand things, you just get used to them.