Binpow - a^n % m in sublinear time

binpow.java

public class Utils {

    public static long mulmod(long a, long b, long mod) {
        return (a * b) % mod;
    }

    public static long binpow(long a, long pow, long mod) {
        if (pow == 0)
            return 1;
        long res = binpow(a, pow / 2, mod);
        res = mulmod(res, res, mod);

        if (pow % 2 == 1)
            res = mulmod(res, a, mod);
        return res;
    }

    public static void main(String[] args) {
        int i = 6;
        long pow = 10;
        long mod = 10;

        long temp = i;
        for(int j = 1; j < pow; j++) {
            temp *= i;
            temp = temp % mod;
        }
        System.out.println(temp);
        System.out.println(binpow(i, pow, mod));
    }
}