模拟测试20191031

水题爆炸，rp++

T1：简单计算

化柿子就好了

$$\sum\limits_{i=0}^{p} \left \lfloor \frac{iq}{p} \right \rfloor$$

$$=\sum\limits_{i=0}^{\left \lfloor  \frac {p}{2} \right \rfloor} \left \lfloor \frac{iq}{p} \right \rfloor+\left \lfloor \frac{(p-i)q}{p} \right \rfloor$$

$$=q\limits \left \lceil \frac{p}{2} \right \rceil $$

$$=(q-1)\limits \left \lceil \frac {p}{2} \right \rceil+\left \lceil \frac{gcd(p,q)}{2} \right \rceil$$

来源：https://www.cnblogs.com/mikufun-hzoi-cpp/p/11770848.html