1716. Calculate Money in Leetcode Bank

Hercy wants to save money for his first car. He puts money in the Leetcode bank every day.

He starts by putting in $1 on Monday, the first day. Every day from Tuesday to Sunday, he will put in $1 more than the day before. On every subsequent Monday, he will put in $1 more than the previous Monday.
Given n, return the total amount of money he will have in the Leetcode bank at the end of the nth day.

 

Example 1:

Input: n = 4
Output: 10
Explanation: After the 4th day, the total is 1 + 2 + 3 + 4 = 10.
Example 2:

Input: n = 10
Output: 37
Explanation: After the 10th day, the total is (1 + 2 + 3 + 4 + 5 + 6 + 7) + (2 + 3 + 4) = 37. Notice that on the 2nd Monday, Hercy only puts in $2.
Example 3:

Input: n = 20
Output: 96
Explanation: After the 20th day, the total is (1 + 2 + 3 + 4 + 5 + 6 + 7) + (2 + 3 + 4 + 5 + 6 + 7 + 8) + (3 + 4 + 5 + 6 + 7 + 8) = 96.
 

Constraints:

1 <= n <= 1000

用等差数列求和公式就行了，每星期是一个等差数列，然后一个星期中每天也是一个等差数列。

class CalculateMoneyInLeetcodeBank : public Solution {
public:
    void Exec() {

    }
    int totalMoney(int n) {
        return (n / 7) * 28 + (n / 7) * (n / 7 - 1) * 7 / 2 + ((n % 7 == 0) ? 0 : ((n % 7) * (1 + n / 7) + (n % 7) * (n % 7 - 1) * 1 / 2));
    }
};