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
return total
- Time Complexity: O(N).
- Space Complexity: O(1).