day12.js

const fs = require('fs');

const lines = fs.readFileSync('day12.txt', {encoding: 'utf-8'}).split('\n').filter(x => x);

const directionToCoord = {
    0: 'E',
    1: 'N',
    2: 'W',
    3: 'S',
}

class Boat {
    constructor() {
        this.x = 0;
        this.y = 0;
        this.direction = 0;
    }

    move(char, number) {
        switch(char) {
            case 'N':
                this.y += number;
                break;
            case 'S':
                this.y -= number;
                break;
            case 'E':
                this.x += number;
                break;
            case 'W':
                this.x -= number;
                break;
            case 'L':
                this.direction = ((this.direction + (number / 90)) + 4)%4;
                break;
            case 'R':
                this.direction = ((this.direction - (number / 90)) + 4)%4;
                break;
            case 'F':
                this.move(directionToCoord[this.direction], number);
                break;
            default:
                throw new Error('Not implemented: ' + char);
                break;
        }
    }

    getPosition() {
        return Math.abs(this.x) + Math.abs(this.y);
    }
}

const boat = new Boat();

lines.forEach(line => {
    const {groups} = /^(?<char>.)(?<number>\d+)$/.exec(line);
    boat.move(groups.char, parseInt(groups.number));
    // console.log(boat.x, boat.y);
})

console.log(boat.getPosition());


class BetterBoat {
    constructor() {
        this.x = 0;
        this.y = 0;
        this.dx = 10;
        this.dy = 1;
    }

    move(char, number) {
        switch(char) {
            case 'N':
                this.dy += number;
                break;
            case 'S':
                this.dy -= number;
                break;
            case 'E':
                this.dx += number;
                break;
            case 'W':
                this.dx -= number;
                break;
            case 'L':
                {
                    let angle = number * Math.PI / 180;
                    let dx = this.dx*Math.cos(angle) - this.dy*Math.sin(angle);
                    let dy = this.dx*Math.sin(angle) + this.dy*Math.cos(angle);
                    this.dx = Math.round(dx);
                    this.dy = Math.round(dy);
                }
                break;
            case 'R':
                {
                    let angle = -number * Math.PI / 180;
                    let dx = this.dx*Math.cos(angle) - this.dy*Math.sin(angle);
                    let dy = this.dx*Math.sin(angle) + this.dy*Math.cos(angle);
                    this.dx = Math.round(dx);
                    this.dy = Math.round(dy);
                }
                break;
            case 'F':
                this.x += number*this.dx;
                this.y += number*this.dy;
                break;
            default:
                throw new Error('Not implemented: ' + char);
                break;
        }
    }

    getPosition() {
        return Math.abs(this.x) + Math.abs(this.y);
    }
}

const betterBoat = new BetterBoat();

// console.log(betterBoat.x, betterBoat.y);
lines.forEach(line => {
    const {groups} = /^(?<char>.)(?<number>\d+)$/.exec(line);
    betterBoat.move(groups.char, parseInt(groups.number));
    // console.log(betterBoat.x, betterBoat.y);
})


console.log(betterBoat.getPosition());