1716. 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

Rust Solution

struct Solution;

impl Solution {
    fn total_money(n: i32) -> i32 {
        let mut res = 0;
        for i in 0..n {
            res += (i % 7) + (i / 7) + 1;
        }
        res
    }
}

#[test]
fn test() {
    let n = 4;
    let res = 10;
    assert_eq!(Solution::total_money(n), res);
    let n = 10;
    let res = 37;
    assert_eq!(Solution::total_money(n), res);
    let n = 20;
    let res = 96;
    assert_eq!(Solution::total_money(n), res);
}

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