Calculating Powers

HugeInt pow(HugeInt x, HugeInt n, HugeInt modulo)

{

if (n == 0)

return 1;

if (n == 1)

return x;

HugeInt squared = x * x % modulo;

if (isEven(n))

return pow(squared, n / 2);

else

return (pow(squared, n/2) * x) % modulo;

}

// If 1 < x < modulo - 1

// but squared == 1,

// then modulo isn’t prime!

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