TLE on Train Schedule

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <climits>
#include <cmath>

typedef long long ll;

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    // freopen("input.txt", "w", stdout); // TODO: REMOVE THIS YOU STUPID ****
    int n = 1e5;
    cout << n << '\n';
    for (int i = 0; i < n; i++) {
        ll a = (ll)sqrt(i);
        a = (a*i)%((ll)sqrt(n));
        if (a < 1) a = 1;
        cout << a << " ";
    }
}

Test 1

Verdict: WRONG ANSWER