Recovery runs weekly progression

main.rs

use std::fmt::{self, Display, Formatter};

#[derive(Copy, Clone)]
struct Seconds(f64);

impl Seconds {
    pub fn compound(self) -> Self {
        Self(self.0 * 1.1)
    }

    pub fn halfway_point(self) -> Self {
        Self(self.0 / 2.0)
    }
}

impl Display for Seconds {
    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
        const SECONDS_PER_MIN: f64 = 60.0;
        
        let mut minutes = self.0.div_euclid(SECONDS_PER_MIN);
        let mut seconds = self.0.rem_euclid(SECONDS_PER_MIN).round();

        if seconds == 60.0 {
            seconds = 0.0;
            minutes += 1.0;
        }

        write!(f, "{}:{:02}", minutes, seconds)
    }
}

fn main() {
    let mut total_run_time = Seconds(15.0 * 60.0);
    
    for i in 0..10 {
        println!("[{}] {} ({})", i, total_run_time, total_run_time.halfway_point());
        total_run_time = total_run_time.compound();
    }
}

[0] 15:00 (7:30)
[1] 16:30 (8:15)
[2] 18:09 (9:05)
[3] 19:58 (9:59)
[4] 21:58 (10:59)
[5] 24:09 (12:05)
[6] 26:34 (13:17)
[7] 29:14 (14:37)
[8] 32:09 (16:05)
[9] 35:22 (17:41)

[0] 24:12 (12:06)
[1] 26:37 (13:19)
[2] 29:17 (14:38)
[3] 32:13 (16:06)
[4] 35:26 (17:43)
[5] 38:58 (19:29)
[6] 42:52 (21:26)
[7] 47:10 (23:35)
[8] 51:52 (25:56)
[9] 57:04 (28:32