CSU 1468: Level Up

题目：

Description

　　Alice loves playing a PC game recently. In this game, you can cost 1 coin to upgrade a role from level 1 to level 2, 2 coins to upgraded a role from level 2 to level 3, 3 coins to upgrade a role from level 3 to level 4, etc.
If Alice has N coins and the level of her role is L, how many levels can her role be upgraded at most? Assume the level of a role has no upper bound.

Input

　　The first line contains the number of test cases T (1 ≤ T ≤ 200).
For each test case, there is only one line with two integers N, L (1 ≤ N, L ≤ 109) as defined above.

Output

　　For each test case, output how many levels can her role be upgraded at most.

Sample Input

5
6 7
7 7
14 7
15 7
10000 3

Sample Output

0
1
1
2
138

代码：

#include<iostream>
using namespace std;

int main()
{
	int t, n, l;
	cin >> t;
	while (t--)
	{
		cin >> n >> l;
		int ans = 0;
		while (n >= l)n -= l, l++, ans++;
		cout << ans << endl;
	}
	return 0;
}