洛谷CF1759B题解

#include<iostream>
#include<cmath>
using namespace std;
void s() {
	int n, tot_lost;
	cin >> n >> tot_lost;
	int maxx = -1;
	int tot_found = 0;
	for (int i = 0; i < n; i++) {
		int x;
		cin >> x;
		tot_found += x;
		maxx = max(maxx, x);
	}
	int tot = tot_found + tot_lost;
	int f = sqrt(double(tot * 2));
	int e = f * (f + 1) / 2;
	if (e == tot && f >= maxx) cout << "YES" << endl;
	else cout << "NO" << endl;
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n;
	cin >> n;
	while (n--) {
		s();
	}
	return 0;
}