cpp
class Solution {
public:
long long c2(long long n)
{
return n > 1? n * (n - 1) / 2 : 0;
}
long long distributeCandies(int n, int limit) {
return c2(n + 2) - 3 * c2(n - limit + 1) + 3 * c2(n - 2 * limit) - c2(n - 3 * limit - 1);
}
};