35 lines
886 B
TypeScript
35 lines
886 B
TypeScript
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import * as fs from "node:fs/promises";
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export function readInput(filename: string): Promise<number[][]> {
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return fs
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.readFile(filename, { encoding: "utf8" })
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.then((lines: string) => lines.split(/\n/))
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.then((lines: string[]) =>
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lines.filter((x) => x).map((x) =>
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x.split(/ +/).map((x) => Number(x))
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)
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);
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}
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export function isSafe(report: readonly number[]): boolean {
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const r = [ ...report ];
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const asc = r[1] - r[0];
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let level = r.shift();
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while (r.length) {
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const next = r.shift();
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const delta = next! - level!;
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if (delta * asc < 0) return false;
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if (Math.abs(delta) < 1 || Math.abs(delta) > 3) return false;
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level = next;
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}
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return true;
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}
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export function solve(reports: number[][]): number {
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return reports.filter(isSafe).length;
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}
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