LeetCode 1716. Calculate Money in Leetcode Bank

Description

https://leetcode.com/problems/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

Explanation

For every 7 numbers, we can increase the start. And we add the number difference between the start and number to the total sum.

Python Solution

class Solution:
def totalMoney(self, n: int) -> int:

total = 0
start = 0

for i in range(1, n + 1):
diff = 7 if i % 7 == 0 else i % 7
total += (start + diff)

if i % 7 == 0:
start = start + 1