December 14, 2018

AOC: Puzzle 2.2 in rust

Input is the same as for 2.1. This time I must find ids that differs by one letter in the same position:

The IDs abcde and axcye are close, but they differ by two characters (the second and fourth). However, the IDs fghij and fguij differ by exactly one character, the third (h and u). Those must be the correct boxes.
What letters are common between the two correct box IDs?

In order to compare ids I going to iteratively replace 1 char in all of them with 0 (which ins not part of original alphabet) and use results of replacement as hash keys while storing original ids to values for the key.

Pseudocode for solution:

ids = get_input_ids
hash = {}

for original_id in ids
  for id_with_1_char_replaced in combinations_with_1_char_replaced(original_id)

solution = hash.values.find { |arr| arr.any? }

def combinations_with_1_char_replaced(original)
    result = []
    original.len.times |idx|
         id_as_array = original.clone()
         id_as_array[idx0] = 0
    return result

Solution in rust:

use std::char;

fn part_two() {
    let input = utils::read_puzzle_input(2);
    let mut results: HashMap<String, Vec<_>> = HashMap::new();
    let mut lines_count = 0;
    let mut ids_count = 0;

    for id in input.lines() {
        let ids = all_valiants_with_1_letter_replaced(id);

        lines_count += 1;

        for id_changed in ids {
            ids_count += 1;
                .and_modify(|vec| vec.push(id.clone()))

    let mut res = vec!();

    for (matcher, ids) in &results {
        if ids.len() > 1 {
            res.push((matcher.clone(), ids.clone()));

    println!("{}", "-".repeat(100));

    for tup in &res {
        println!("{:?}", tup);

    println!("{}", "-".repeat(100));

    println!("Res.len: {:?}", res.len());
    println!("Keys: {}", results.keys().len());
    println!("Values: {}", results.values().fold(0, |acc, arr| acc + arr.len()));
    println!("Lines: {}, ids: {}", lines_count, ids_count);

fn all_valiants_with_1_letter_replaced(id: &str) -> Vec<String> {
    let mut result: Vec<String> = vec!();
    let id_map = id.chars().collect::<Vec<char>>();
    let size = id.len();

    for idx in 0..size {
        let mut cur_map = id_map.clone();
        cur_map[idx] = '0';

    return result;

Running the code:

➜  aoc2018 git:(master) ✗ cargo run --bin 2
warning: unused manifest key: package.edition
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/2`
("cvgywxqubnuaefmsl0jdrpfzyi", ["cvgywxqubnuaefmsldjdrpfzyi", "cvgywxqubnuaefmslkjdrpfzyi"])
Res.len: 1
Keys: 6499
Values: 6500
Lines: 250, ids: 6500

What letters are common between the two correct box IDs?

Removing 0 from hash key: "cvgywxqubnuaefmsljdrpfzyi". Submitting.

Your puzzle answer was cvgywxqubnuaefmsljdrpfzyi. Both parts of this puzzle are complete! They provide two gold stars: **

The Code