Simple Math ARC111

Simple Math ARC111 - A 数论，思维

题意

给出(N,M)，求(lfloorfrac{10^N}{M} floor)除以(M)的余数

[1leq N leq 10^{18}\ 1leq M leq 10000 ]

分析

(lfloorfrac{10^N}{M} floor equiv lfloorfrac{10^N}{M} floor - kM equiv lfloorfrac{10^N - kM^2}{M} floor (mod M))

于是先求分子即可

代码

int main(){
	ll n = rd();
	ll m = rd();
	cout << ksm(10,n,m * m) / m;
}