Code shared from the Rust Playground

playground.rs

fn find_subseq(s: &[u8]) -> u8 {
    let mut res: u8 = 1;
    let mut i = 0;
    while (i < s.len() - 1) && s[i] < 255 && (s[i] + 1 == s[i + 1]) {
        res += 1;
        i += 1;
    }
    return res;
}

pub fn longest_incrementing_subslice(s: &[u8]) -> &[u8] {
    let mut res = (0, 1);
    let mut el = 0;
    while el < s.len() - 1 {
        let subl = find_subseq(&s[el..s.len()]);
        if subl > res.1 {
            res.0 = el;
            res.1 = subl;
        }
        el = el + subl as usize;
    }
    return &s[res.0..res.0 + res.1 as usize];
}

fn main() {
    let data = &[2, 5, 2, 253, 254, 255, 1];
    let result = longest_incrementing_subslice(data);
    println!("{:?}", result);
}