timus 2025. Line Fighting

#include <cstdio>
int main()
{
int N, K, T;
while (scanf("%d", &T) != EOF) {
while (T--) {
scanf("%d %d", &N, &K);
int k[K+1];
int num1 = N / K, num2 = N % K;
for (int i = 1; i <= K; ++i) {
if (i <= num2) {
k[i] = num1 + 1;
} else {
k[i] = num1;
}
}
int ans = 0;
for (int i = 1; i <= K; ++i) {
ans += k[i] * (N - k[i]);
for (int j = 1; j < i; ++j)
ans -= k[i] * k[j];

}
printf("%d\n", ans);
}
}
return 0;
}