I was just doing virtual on 1338A - Powered Addition.

I wrote the following code: 121160133

and it out puts "63" on this test: N = 5, A = {-9, -2, -2, 7, 5} on both versions of C++17.

The probably problematic part is here:

int ans = 0, mx = -1e9;
for (int i = 0; i < N; i++) {
    mx = max(mx, A[i]);
    ans = max(ans, __lg(mx - A[i]) + 1);
    if(ans == 63){
        cout<<"ERROR\n";
        assert(false);
    }
}
cout << ans << '\n';

If I output i and ans, ans is changed to 63 at i = 2.

But I thought __lg(0) is -1? Also in custom invocation, the error message never appears, and the code is never terminated by assert(false).

Does anyone have any idea?

For data structures such as persistent segment tree or treaps, is it OK if I submit a solution that DOESN'T delete the pointers I used? Also, is there any method more convenient than recursively delete all the trees at the end of my program?