给出两种阶乘计算的C++实现如下：

int factorial1(int n) {
    if (n <= 1) return 1;
    return n * factorial1(n - 1);
}

int factorial2(int n) {
    int acc = 1;
    while (n > 1) {
        acc = n * acc;
        n = n - 1;
    }
    return acc;
}