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

## Solution 1: Simulation

Increase the amount by 1 everyday, the decrease 6 after every sunday.

Time complexity: O(n)
Space complexity: O(1)

## C++

Could also be solved using Math in O(1)

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