group_possibilities_by_score.rs

fn group_possibilities_by_score(
    guess: &[i32; N],
    possibilities: &Vec<[i32; N]>
) -> [Vec<[i32; N]>; NN] {
    let mut possibilities_by_score: [Vec<[i32; N]>; NN] = Default::default();
    for i in 0..NN {
        possibilities_by_score[i] = vec![];
    }

    for possibility in possibilities {
        let mut new_possibility = possibility.clone();
        let score = compute_score(&guess, &new_possibility);
        let score_index = encode_score(score);
        possibilities_by_score[score_index].push(new_possibility)
    }
    return possibilities_by_score;
}

fn compute_score(guess: &[i32; N], secret: &[i32; N]) -> (i32, i32) {
    let mut perfect_matches = 0;
    for i in 0..guess.len() {
        if guess[i] == secret[i] {
            perfect_matches += 1;
        }
    }

    let mut look_up_position: [bool; D] = [false; D];
    for i in 0..guess.len() {
        let position = (guess[i] - 1) as usize;
        look_up_position[position] = true;
    }
    let mut any_matches = 0;
    for i in 0..secret.len() {
        let position = (secret[i] - 1) as usize;
        if look_up_position[position] {
            any_matches += 1;
        }
    }
    let imperfect_matches = any_matches - perfect_matches;
    return (perfect_matches, imperfect_matches);
}

fn encode_score(score: (i32, i32)) -> usize {
    let n = (N + 1) as i32;
    return (score.0 * n + score.1) as usize;
}