求问这题第二种询问单次时间复杂度是多少

ll p=x,nowt=t;
while(nowt>=0){
    REV(i,62,0){
        ll d=1ll<<i;
        if(d>nowt) continue;
        if(p+d<((nowt-d)>>1)) p+=d,nowt-=d;
    }
    while(p<((nowt)>>1)) ++p,--nowt;
    if(p>(nowt)>>1) break;
    p=0,--nowt;
}
cout<<p<<endl;