堅森-學習大小事

方法1:

• 兩層迴圈處理

方法2: 

• 一層迴圈處理

int main() {
  int num = 0;
  int each_sum = 1;
  int total_sum = 1;
  cout << "輸入一個數字: " << endl;
  cin >> num;
  int i = 1;
  for (i; i <= num; i++) {
    each_sum = 1*i;
    total_sum *= each_sum;
  }

  cout << "計算" << num << "!: " << total_sum << endl;
  return 0;
}

• 計算 1! + 2! + 3! + ….+ n!

int main() {
  int num = 0;
  int each_sum = 1;
  int total_sum = 0;

  cout << "輸入一個數字: " << endl;
  cin >> num;
  int i = 1;
  for (i; i <= num; i++) {
    each_sum *= i;
    total_sum += each_sum;
  }

  cout << "1!+2!+3!+...+n! = " << total_sum << endl;
  return 0;
}