Power Modulo - Algorithm

Instead of recursion, you can use an iterative approach. Start with $result = 1$ and process each bit of $n$ from right to left.

If the current bit is 1, multiply $result$ by the current power of $x$. Then square $x$ and move to the next bit.

This works because any exponent $n$ can be written in binary. For example, $13 = 8 + 4 + 1 = 2^3 + 2^2 + 2^0$, so $x^{13} = x^8 \times x^4 \times x^1$.