牛客练习赛43 Tachibana Kanade Loves Probability(快速幂)

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<queue>
#define ll long long int
using namespace std;
inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
inline ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
int moth[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int dir[4][2]={1,0 ,0,1 ,-1,0 ,0,-1};
int dirs[8][2]={1,0 ,0,1 ,-1,0 ,0,-1, -1,-1 ,-1,1 ,1,-1 ,1,1};
const int inf=0x3f3f3f3f;
const ll mod=1e9+7;
ll m,n,k1,k2;
ll q_pow(ll a,ll n,ll mod){
    ll ans=m; ll base=a;
    while(n){
        if(n&1) ans=(ans*base)%mod;
        base=base*base%mod;
        n>>=1;
    }
        return ans;
}
int main(){
    //ios::sync_with_stdio(false);
    int t;
    scanf("%d",&t);
    while(t--){
        scanf("%lld%lld%lld%lld",&m,&n,&k1,&k2);
        ll f=q_pow(10,k1-1,n);
        ll i=k1;
        while(1){
            f*=10;
            printf("%lld",f/n);
            f%=n;
            i++;
            if(i==k2+1)
            break;
        }
        printf("\n");
    }
}