EnEnCode

pub fn day19(input: &str) -> (u64, u64) {
    fn recur_helper<'a>(pat: &'a str, towels: &[&str], map: &mut HashMap<&'a str, u64>) -> u64 {
        let mut hits = 0;
        let mut towel_subset = towels;
        for l in 1..=pat.len() {
            let test_pat = &pat[0..l];
            match towel_subset.binary_search(&test_pat) {
                Ok(idx) => {
                    if pat[l..].is_empty() {
                        return hits + 1;
                    } else if let Some(&v) = map.get(&pat[l..]) {
                        hits += v;
                    } else {
                        let v = recur_helper(&pat[l..], towels, map);
                        map.insert(&pat[l..], v);
                        hits += v;
                    }

                    towel_subset = &towel_subset[idx..];
                    let end = towel_subset.partition_point(|&x| x.starts_with(test_pat));
                    towel_subset = &towel_subset[..end];
                    if towel_subset.is_empty() {
                        return hits;
                    }
                }
                Err(idx) => {
                    towel_subset = &towel_subset[idx..];
                    let end = towel_subset.partition_point(|&x| x.starts_with(test_pat));
                    towel_subset = &towel_subset[..end];
                    if towel_subset.is_empty() {
                        return hits;
                    }
                }
            }
        }
        hits
    }
    let mut part1 = 0;
    let mut part2 = 0;
    let mut lines = input.lines();
    let mut towels = lines.next().unwrap().split(", ").collect::<Vec<_>>();
    towels.sort();
    let mut map = HashMap::new();
    for pat in lines.skip(1) {
        let tmp = recur_helper(pat, &towels, &mut map);
        part2 += tmp;
        if tmp > 0 {
            part1 += 1;
        }
    }
    (part1, part2)
}