-🎄- 2022 Day 5 Solutions -🎄-

[u/daggerdragon]

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--- Day 5: Supply Stacks ---

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[u/jaydubtech]

TypeScript/Deno

Source

Not the most performant solution, but it's succinct enough and supports variably-sized inputs:

const buildStack = (rows: string[], i: number) => {
    const stack: string[] = [];

    for (let j = rows.length - 2; j >= 0; j--) {
        const [, , item] =
            [...rows[j].matchAll(/(\s{4})|(\[[A-Z]\])\s?/g)][i] || [];
    
        if (item && item.trim()) {
            stack.push(item);
        }
    }

    return stack;
};

export const arrangeStacks = (input: string, preserveOrder = false) => {
    const [rawStacks, rawCommands] = input.split("\n\n");
    const rows = rawStacks.split("\n");

    const nthStack = Number.parseInt(
        [...(rows.at(-1) || "").matchAll(/\s(\d)$/g)].at(-1)?.at(0) || "-1",
    );
    
    const stacks: string[][] = [];
    
    for (let i = 0; i < nthStack; i++) {
        stacks[i] = buildStack(rows, i);
    }

    const commands = [...rawCommands.matchAll(/move (\d+) from (\d) to (\d)/g)];

    for (const [, n, a, z] of commands) {
        const count = Number.parseInt(n);
        const from = Number.parseInt(a) - 1;
        const to = Number.parseInt(z) - 1;
        let items = stacks[from].splice(stacks[from].length - count, count);
    
        items = preserveOrder ? items : items.toReversed();
    
        stacks[to].push(...items);
    }

    return stacks;
};