this repo has no description
tried product of steps to first end node
didn't work! noticed this worked for the example data, but my answer is too high
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2023/day08/part2.ts
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2023/day08/part2.ts
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type Node = { L: string; R: string };
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type Network = Record<string, Node>;
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export function answer(input: string): number {
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export function answer(input: string) {
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const [instructions, , ...networkRaw] = input.split("\n");
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const network: Network = networkRaw.reduce((network, line) => {
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return { ...network, [id]: { L, R } };
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}, {});
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const pathsFinished = (paths: string[]): boolean =>
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paths.every((p) => p.endsWith("Z"));
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const step = (paths: string[], dir: keyof Node): string[] =>
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paths.map((c) => network[c][dir]);
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const paths = Object.keys(network).filter((n) => n.endsWith("A"));
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return BigInt(
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paths
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.map((p) => countSteps(p, network, instructions))
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.reduce((total, x) => (total *= x), 1),
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);
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}
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let paths = Object.keys(network).filter((n) => n.endsWith("A"));
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function countSteps(
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start: string,
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network: Network,
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instructions: string,
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): number {
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let currentNode = start;
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let stepCount = 0;
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console.log(`network: ${Object.keys(network).length}`);
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console.log(`paths: ${paths.length}`);
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while (!pathsFinished(paths)) {
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while (!currentNode.endsWith("Z")) {
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for (const dir of instructions.split("")) {
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logPaths(stepCount, paths);
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paths = step(paths, dir as keyof Node);
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currentNode = network[currentNode][dir as keyof Node];
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stepCount++;
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if (pathsFinished(paths)) break;
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if (currentNode.endsWith("Z")) break;
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}
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}
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return stepCount;
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}
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function logPaths(stepCount: number, paths: string[]) {
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console.log(
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`${stepCount.toString().padStart(20, "0")} ${paths
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.map((p) => (p.endsWith("Z") ? "x" : "."))
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.join("")}`,
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);
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}
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if (import.meta.main) {