day02/src/main.rs


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use std::io;

struct Range {
    start: i64,
    end: i64,
}

impl Range {
    fn new<'a>(mut iter: impl DoubleEndedIterator<Item = &'a str>) -> Self {
        let start = iter.next().unwrap().parse::<i64>().unwrap();
        let end = iter.next().unwrap().parse::<i64>().unwrap();
        Self { start, end }
    }
}

fn is_invalid(value: i64) -> bool {
    let tmp = value.to_string();
    /*
    if tmp.len() % 2 != 0 {
        return false
    }
    let (a, b) = tmp.split_at(tmp.len() / 2);
    return a == b;
     */
    for x in 1..=tmp.len() / 2 {
        if tmp.len() % x != 0 {
            continue;
        }
        let (first, rest) = tmp.split_at(x);
        let mut rest2 = rest;
        let mut all_match = true;
        for _ in 0..tmp.len() / x - 1 {
            match rest2.strip_prefix(first) {
                Some(value) => rest2 = value,
                None => {
                    all_match = false;
                    break;
                }
            };
        }
        if all_match {
            return true;
        }
    }
    false
}

fn invalid(range: &Range) -> i64 {
    let mut total = 0;
    for i in range.start..=range.end {
        if is_invalid(i) {
            total += i;
        }
    }
    total
}

fn main() {
    let mut buffer = String::new();
    io::stdin().read_line(&mut buffer).unwrap();
    let mut total = 0;
    for range in buffer
        .trim_end()
        .split(',')
        .map(|x| Range::new(x.split('-')))
    {
        total += invalid(&range);
    }
    println!("Invalid: {}", total);
}