alphametics

lib.rs

    let permutations = (0u8..10u8).permutations(letters.len());
<!--  105s   -->
let possible_dicts: Vec<BTreeMap<char, u8>> = permutations
        .filter_map(|permutation| {
            let dict: BTreeMap<char, u8> = letters.iter().copied().zip(permutation).collect();
            if dict.iter().any(|(c, &n)| leading.contains(c) && n == 0) {
                None
            } else {
                Some(dict)
            }
        })
        .collect();
<!--    250s +            -->
    // for permutation in permutations {
    //     let dict: BTreeMap<char, u8> = letters.iter().copied().zip(permutation).collect();
    //     if dict.iter().any(|(c, &n)| leading.contains(c) && n == 0) {
    //         continue;
    //     } else {
    //         possible_dicts.push(dict);
    //     }
    // }