546A - Soldier And Bananas
28 Dec 2020 — Tags: easy,summation — URLReduce summation to closed form and solve the equation.
Time complexity: $O(1)$
Memory complexity: $O(1)$
Click to show code.
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
int main(void)
{
ios::sync_with_stdio(false), cin.tie(NULL);
int k, n, w;
cin >> k >> n >> w;
int x = max(k * (w * (w + 1)) / 2 - n, 0);
cout << x << endl;
return 0;
}