Monk's Encounter With Polynomial - Binary Search (HackerEarth)

/*
Ax^2+Bx+c>=K
found to be smallest value of x such that above condition in to be followed.
*/
#include<bits/stdc++.h>
using namespace std;
int main()
{
	int t;
	cin >> t;
	while(t--)
	{
		long long  a,b,c;
		cin >> a >> b >> c;
		long long k;
		cin >> k;
		long long ans;
		long long low=0;
		long long high=1000000;
		while(low<=high)
		{
			long long  mid=low+(high-low)/2;
			long long val=a*mid*mid+b*mid+c;
			if(val>=k)
			{
				ans=mid;
				high=mid-1;
			}
			else
			{
				low=mid+1;
			}
		}
		cout<<ans<<'\n';
	}
	return 0;
}