projecteuler.net/019/src/main.rs

use time::Date;
use time::Month;
use time::Duration;

fn main() {
    let d_begin = Date::from_calendar_date(1901, Month::January, 1).unwrap();
    let d_end = Date::from_calendar_date(2000, Month::December, 31).unwrap();
    let dt = Duration::DAY;
    let mut day_count = 0u32;
    let mut sundays_count = 0u32;
    let mut di = d_begin.clone();
    while di != d_end {
        if di.weekday() == time::Weekday::Sunday {
            if di.day() == 1 {
                sundays_count += 1;
            }
        }
        //println!("{}", di.weekday());
        di = di.checked_add(dt).unwrap();
        day_count += 1;
    }

    println!("day_count: {}", day_count);
    println!("sundays count: {}", sundays_count);
}