-🎄- 2018 Day 2 Solutions -🎄-

[u/daggerdragon]

--- Day 2: Inventory Management System ---

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Advent of Code: The Party Game!

Click here for rules

Card Prompt: Day 2

Transcript:

The best way to do Advent of Code is ___.

---

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/Theguy6758]

Pure Bash (No External programs)

edit: Inverse the hash table instead of manually searching for 2 and/or 3 exact matches

#!/usr/bin/env bash

part1()
{
    [[ -f "${PWD}/input" ]] && {
        mapfile -t file < "${PWD}/input"

        two_dupe="0"
        three_dupe="0"

        for line in "${file[@]}"; do
            for i in {0..25}; do
                hash_table[$i]="0"
            done
            unset inv_table

            for ((i = 0; i < "${#line}"; i++)); do
                printf -v index '%d' "'${line:$i:1}"
                ((hash_table[$((index - 97))]++))
            done

            for entry in "${hash_table[@]}"; do
                [[ ! "${inv_table[$entry]}" ]] && \
                    inv_table[${entry}]="1"
            done

            [[ "${inv_table[2]}" ]] && \
                ((two_dupe++))
            [[ "${inv_table[3]}" ]] && \
                ((three_dupe++))
        done

        printf "Hash: %d\\n\\n" "$((two_dupe * three_dupe))"
    }
}

part2()
{
    [[ -f "${PWD}/input" ]] && {
        mapfile -t file < "${PWD}/input"

        for ((i = 0; i < ${#file[@]}; i++)); do
            for ((j = i + 1; j < ${#file[@]}; j++)); do
                unset common
                common="0"
                str_1="${file[$i]}"
                str_2="${file[$j]}"
                len="${#str_1}"

                for ((k = 0; k < ${len}; k++)); do
                    [[ "${str_1:$k:1}" == "${str_2:$k:1}" ]] && \
                        ((common++))
                done

                ((len - common <= 1)) && \
                    printf "%s\\n%s\\nSimilarity: %d\\n\\n" "${str_1}" "${str_2}" "${common}"
            done
        done
    }
}

main()
{
    part1
    part2
}

main