Bit representation can do ? 1) to indicate whether there exist an element \/ a number \/ a valid operation here

Math.pow(x,y)

4 ^ 5 = 4 ^ 4 * 4

0 1 0 1

16*16*16*16 16*16 16 4

//assume x > 0, y > 0, no overflow.
public int pow(int x, int y) {
    int runningProduct = 1;
    int y = 1;
    while (y != 0) {
        if (x & 1 == 1) {
            ret = ret * runningProduct;
        }
        runningProduct *= runningProduct;
        y >> 1;
    }
    return ret;
}