123 lines
3 KiB
JavaScript
123 lines
3 KiB
JavaScript
const { Glib, Vector, twodee } = require('../../lib');
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const LEFT = new Map([
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[twodee.DIRECTIONS.UP.string, twodee.DIRECTIONS.LEFT],
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[twodee.DIRECTIONS.LEFT.string, twodee.DIRECTIONS.DOWN],
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[twodee.DIRECTIONS.DOWN.string, twodee.DIRECTIONS.RIGHT],
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[twodee.DIRECTIONS.RIGHT.string, twodee.DIRECTIONS.UP],
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]);
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const RIGHT = new Map([
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[twodee.DIRECTIONS.UP.string, twodee.DIRECTIONS.RIGHT],
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[twodee.DIRECTIONS.RIGHT.string, twodee.DIRECTIONS.DOWN],
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[twodee.DIRECTIONS.DOWN.string, twodee.DIRECTIONS.LEFT],
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[twodee.DIRECTIONS.LEFT.string, twodee.DIRECTIONS.UP],
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]);
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const INSTRUCTIONS1 = {
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N: (count, state) => {
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return {
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...state,
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location: state.location.add(twodee.DIRECTIONS.UP.multiply(count)),
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};
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},
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S: (count, state) => {
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return {
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...state,
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location: state.location.add(twodee.DIRECTIONS.DOWN.multiply(count)),
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};
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},
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E: (count, state) => {
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return {
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...state,
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location: state.location.add(twodee.DIRECTIONS.RIGHT.multiply(count)),
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};
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},
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W: (count, state) => {
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return {
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...state,
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location: state.location.add(twodee.DIRECTIONS.LEFT.multiply(count)),
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};
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},
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F: (count, state) => {
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return {
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...state,
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location: state.location.add(state.direction.multiply(count)),
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};
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},
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L: (count, state) => {
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let direction = state.direction;
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for (let i = 0; i < count; i += 90) {
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direction = LEFT.get(direction.string);
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}
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return {
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...state,
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direction,
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};
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},
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R: (count, state) => {
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let direction = state.direction;
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for (let i = 0; i < count; i += 90) {
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direction = RIGHT.get(direction.string);
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}
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return {
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...state,
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direction,
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};
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},
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};
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const INSTRUCTIONS2 = {
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...INSTRUCTIONS1,
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F: (count, state) => {
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return {
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...state,
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ship: state.ship.add(state.location.multiply(count)),
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};
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},
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// todo: (soon) implement a matrix library so this gets better
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L: (count, state) => {
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let location = state.location;
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for (let i = 0; i < count; i += 90) {
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location = new Vector(-location.v[1], location.v[0]);
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}
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return {
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...state,
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location,
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};
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},
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R: (count, state) => {
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let location = state.location;
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for (let i = 0; i < count; i += 90) {
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location = new Vector(location.v[1], -location.v[0]);
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}
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return {
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...state,
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location,
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};
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},
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};
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const solve = (input, ops, start = twodee.ORIGIN) =>
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Glib.fromLines(input, ops)
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.map(([instruction, ...number]) => ({
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instruction,
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count: BigInt(number.join('')),
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}))
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.reduce(
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(state, { instruction, count }) => {
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return ops[instruction](count, state);
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},
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{
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location: start,
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direction: twodee.DIRECTIONS.RIGHT,
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ship: twodee.ORIGIN,
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},
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);
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module.exports = {
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1: (input) => solve(input, INSTRUCTIONS1).location.distance(twodee.ORIGIN),
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2: (input) =>
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solve(input, INSTRUCTIONS2, new Vector(10, 1)).ship.distance(twodee.ORIGIN),
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};
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