C题 没开long double导致wa 请教各位大佬

如题 这题没开long double导致最后通过率是百分之九十多，开了就a了，请教各位是什么原因呢 有什么hack数据呀

#include <bits/stdc++.h>

using namespace std;
typedef long long LL;


void solve(){
    LL n;
    cin>>n;
    LL add = log2((long double)n);
//     LL add2 = log2(n);
//     cout<<add<<" "<<add2<<endl;
    LL last=add;
    LL res;
    do{
        last=add;
        res = 2ll*(add+n);
        add = log2((long double)res)-1; 
    }while (add!=last);
    cout<<res<<endl;

}


int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int T;
    cin>>T;
    while(T--){
        solve();
    }

    return 0;
}