摘要:
1.$n!$ 中因子 $k$ 的个数: 以 $k=5$ 为例: 代码: 2.$gcd$相关: $gcd(a,b)=1 \Rightarrow gcd(a,a b)=1$ 3.欧拉函数相关: (1)求出小于等于 $n$ 且与 $n$ 互质的数的和: $$ans=\begin{cases} \frac{ 阅读全文
摘要:
题意: You task is to find minimal natural number $N$, so that $N!$ contains exactly $Q$ zeroes on the trail in decimal notation. As you know $N! = 1 2 . 阅读全文