49 lines
1.7 KiB
TypeScript
49 lines
1.7 KiB
TypeScript
import { inputNumbers } from "./common.ts";
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/** This solution is relatively simple. Keep track of the last depth we
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* measured in `lastDepth` (skipping the first line of input by defaulting it
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* to `Number.MAX_VALUE`) and compare it to each line of input as we read it.
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* Once we've compared, set the `lastDepth` to the current depth for the next
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* iteration.
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*
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* This solution should be O(n) for compute and O(n) for memory since we
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* iterate the input once and only read a line at a time, we actually have O(1)
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* memory, but since the input is on disk, that's kind of unfair to say.
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*/
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export async function part1(
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input: AsyncIterableIterator<number>,
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): Promise<number> {
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let increases = 0;
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let lastDepth = Number.MAX_VALUE;
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for await (const depth of input) {
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if (depth > lastDepth) increases++;
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lastDepth = depth;
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}
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return increases;
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}
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console.log("Part 1", await part1(await inputNumbers("1")));
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/** Since the windows we need to compare overlap, we really only need to
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* compare the values unique to each window, which will be the first of the
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* first window and the last of the last window. Since the windows have size 3,
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* we really only need to compare a value with the "three-lines-ago" value.
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* This solution otherwise is identical to the previous one.
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*/
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export async function part2(
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input: AsyncIterableIterator<number>,
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windowSize = 3,
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): Promise<number> {
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let increases = 0;
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const window: number[] = await Promise.all(Array.from(
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Array(windowSize),
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async (_x, _i) => parseInt((await input.next()).value),
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));
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for await (const depth of input) {
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if (depth > (window.shift() as number)) increases++;
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window.push(depth);
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}
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return increases;
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}
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console.log("Part 2", await part2(await inputNumbers("1")));
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