C++ :

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<vector>
#include<queue>
#include<map>
using namespace std;
//const long long N=;
long long G,g,t,c,gg,jk,gr,sy,sj,gs1,gs2,ling=0;
int main()
{
	cin>>G;
	while (G--)
	{
		cin>>g>>t>>c;
		jk=0;//閲戠熆 
		gr=1;//宸ヤ汉 
		for (int i=1;i<=t;i++)
		{
			sj=t-i+1;//鍓╀綑鏃堕棿 
			if (sj>c) 
			{
				gs1=max(ling,g-sj*gr)/sj;//鐢卞墿浣欓噾鐭垮喅瀹氱殑宸ヤ汉鏁伴噺
				gs2=jk/c;//鐢遍挶鍐冲畾鐨勫伐浜烘暟閲?
				gr+=min(gs1,gs2);
				jk-=c*min(gs1,gs2);
				if (jk>=c)
				{
					sy=min(g-sj*gr,sj);
					if (sy>c) gr++,jk-=c;
				}
			}
			if (g>=gr) g-=gr,jk+=gr; else jk+=g,g=0;
		}
		cout<<jk<<endl;
	}
	return 0;
}