17번

#include<iostream>
#include<vector>
#include<string.h>
using namespace std;

int main()
{
	int N;
	int sum=0;
	cin >> N;
	vector<vector<int> > arr(N,vector<int>(2));

	for (int i = 0; i < N; i++)
	{
		for (int j = 0; j < 2; j++)
		{
			cin >> arr[i][j];
		}
	}
	for (int i = 0; i < N; i++)
	{
		sum = 0;
			for (int k = 1; k <= arr[i][0]; k++)
			{
				
				sum = k + sum;
			}
		
		
		if (arr[i][1] == sum)
		{
			cout << "YES" << endl;
		}
		else cout << "NO" << endl;

	}
}