long result = 1;
public long stratum(long num){
// 递归出口,当 num = 0 or 1 的时候,结束方法
if (num == 0 || num == 1) {
return result;
}
// result = result * stratum(num--);
result *= num;
num --;
return stratum(num);
}
public static void main(String[] args) {
Demo07 d7 = new Demo07();
long stratum = d7.stratum(4);
System.out.println(stratum);
}
}