Run this O(n^2)
program in CF custom test
#include "bits/stdc++.h"
using namespace std;
long long n;
int main() {
cin >> n;
for(long long i = 1; i <= n; i++) {
for(long long j = 1; j <= n; j++) {
if((i ^ j) == 0) {
if(i != j) {
cout << "NO!\n";
return 0;
}
}
}
}
cout << "YES\n";
}
with n = 100000000000
You would expect it to be much longer than 1 second, but it takes
15 ms