Calculate Money in Leetcode Bank — LeetCode 1716 Python Solution

The problem

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

Example

Input

n = 4

Output

10

Explanation

After the 4th day, the total is 1 + 2 + 3 + 4 = 10.

Python solution

class Solution:
    def totalMoney(self, n: int) -> int:
        k, b = divmod(n, 7)
        s1 = (28 + 28 + 7 * (k - 1)) * k // 2
        s2 = (k + 1 + k + 1 + b - 1) * b // 2
        return s1 + s2

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 1716. Calculate Money in Leetcode Bank is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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