在 GeeksForGeeks 是以下功能：

// Returns (a * b) % mod
long long moduloMultiplication(long long a,
                               long long b,
                               long long mod)
{
    long long res = 0;  // Initialize result

    // Update a if it is more than
    // or equal to mod
    a %= mod;

    while (b)
    {
        // If b is odd, add a with result
        if (b & 1)
            res = (res + a) % mod;

        // Here we assume that doing 2*a
        // doesn't cause overflow
        a = (2 * a) % mod;

        b >>= 1;  // b = b / 2
    }

    return res;
}

使用它代替

x = (x*x) % p;

即，

x = moduloMultiplication(x, x, p);

，而不是

res = (res*x) % p

即，

res = moduloMultiplication(res, x, p);