818F - Level Generation - CodeForces Solution

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int q;
    cin >> q;
    while(q--) {
        ll n;
        cin >> n;
        ll l = 1, r = n;
        while(r - l > 1) {
            ll mid = l + (r - l) / 2;
            ll val = mid * (mid - 1) / 2;
            if(val > n - mid) {
                r = mid;
            }
            else {
                l = mid; 
            }
        }
        cout << max((l * (l - 1) / 2) + n - l, (n - r) * 2) << endl;
    }
    return 0;
}