//c++ code

include

using namespace std;

define endl '\n'

define ig cin.ignore()

define GET_FASTER ios_base::sync_with_stdio(false); cin.tie(NULL)

typedef long long int ll; const ll mx= LLONG_MAX; const ll mn= LLONG_MIN; const ll MOD= 1e9+7; bool descending_order(int x, int y){return x>y;}

long long nth_term(long long n){ return (n+(n*n))/2; }

int main(){

GET_FASTER;

int t;
cin>> t;

while(t--){
    long long n,m;
    cin>> n>> m;

    long long rem= n %m;
    long long div= n/m;
    long long tem= m-1;

    long long result;

    result = ((nth_term(tem)*div)+ nth_term(rem));

    cout<< result<< endl;

}


return 0;

}

Power-efficient - Integrated GPUs consume less power than dedicated GPUs, which makes them ideal for use in laptops and other mobile devices. https://upgpu.com/best-gpu-for-i5-9400f/

Gauss's summation implemented in Python.

def solve(n, m):
    return ((m-1)*m//2)*(n//m)+(n%m)*(n%m+1)//2

Explanation: Gauss's formula for summation states that the sum from 1 to N for any natural number, N, can be calculated arithmetically:

The problem statement implies an approach where one would loop from 1 up to n, taking mod m at each step.
However, with some out-of-the-box thinking, by applying the mod m ahead of time, you will see that in fact we are summing from 1 to m-1 over and over.
The number of times we take this sum is equal to

how to run out of memory: it supposed to work, while the n array is small XD

def solve(n, m):
    tot = 0
    for num in range(1,n+1):
        tot += num%m
    return tot

C# function prototype provided won't work. Should be long not int.