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++
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// Author: huahua class Solution { public: int totalMoney(int n) { int total = 0; for (int d = 0, m = 1; d < n; ++d) { total += m++; if (d % 7 == 6) m -= 6; } return total; } }; |
Could also be solved using Math in O(1)