链接：https://ac.nowcoder.com/acm/contest/548/B

快速幂取模+快速除

#include<bits/stdc++.h>
using namespace std;
long long m,n,k1,k2;
long long powerMod(int a,long long b){
	long long ans=m;
	a=a%n;
	while(b>0){
		if(b&1) ans=(long long)ans*a%n;
		a=(long long)a*a%n;
		b/=2;
	}
	return ans;
}
int main(){
	std::ios::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--){
        cin>>m>>n>>k1>>k2;
        
        long long p,q;
        p=powerMod(10,k1-1);
        for(int i=k1;i<=k2;i++)
	    {
		    cout<<p*10/n; 
		    p=p*10%n;
	    }
	    cout<<endl;
        
    }
}