大家伙看看,这个会不会比普通的快速幂快呢?
ll ksm(ll a,ll b,ll mod)
{
a%=mod;
if(b==0ll)return 1ll%mod;
if(b==1ll)return a%mod;
if(b==2ll)return ((a%mod)*(a%mod))%mod;
return ((((ksm(a,b/3ll,mod)%mod)*(ksm(a,b/3ll,mod)%mod))%mod)*(((ksm(a,b/3ll,mod)%mod)*(ksm(a,b%3ll,mod)%mod))%mod))%mod;
}