A. Contest Start1000 / 思维

Posted 2021-11-11 幽殇默

https://codeforces.com/problemset/problem/1539/A
详细题解

#include<bits/stdc++.h>
using namespace std;
typedef long long int LL;
int main(void)
{
	LL t; cin>>t;
	while(t--)
	{
		LL n,x,t; cin>>n>>x>>t;
		if(n*x<=t) cout<<n*(n-1)/2<<endl;
		else
		{
			LL cnt=t/x;
			LL num=n-cnt;
			cout<<num*cnt+cnt*(cnt-1)/2<<endl;
		}
	}
	return 0;
}