1716. Calculate Money in Leetcode Bank

Description

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

Solutions

Solution 1

Python Code
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class Solution:
    def totalMoney(self, n: int) -> int:
        a, b = divmod(n, 7)
        return (28 + 28 + 7 * (a - 1)) * a // 2 + (a * 2 + b + 1) * b // 2

Java Code
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class Solution {
    public int totalMoney(int n) {
        int a = n / 7, b = n % 7;
        return (28 + 28 + 7 * (a - 1)) * a / 2 + (a * 2 + b + 1) * b / 2;
    }
}

C++ Code
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class Solution {
public:
    int totalMoney(int n) {
        int a = n / 7, b = n % 7;
        return (28 + 28 + 7 * (a - 1)) * a / 2 + (a * 2 + b + 1) * b / 2;
    }
};

Go Code
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func totalMoney(n int) int {
	a, b := n/7, n%7
	return (28+28+7*(a-1))*a/2 + (a*2+b+1)*b/2
}