AoC 2019 day 10

day10.js

function Asteroid(position)
{
    this.position = position;
    this.slopes = new Map();
}

Asteroid.prototype.slopeAndDistance = function(other)
{
    let xdiff = (other.position.x - this.position.x);
    let ydiff = (other.position.y - this.position.y);
    let slope =  xdiff / ydiff;
    
    this.slopes.set(other, {slope:slope, sign:Math.sign(ydiff)});
};

Asteroid.prototype.seeCount = function()
{
    let count = 0;
    let slopeSeen = [];

    for(let [asteroid, slope] of this.slopes)
    {
        if(typeof(slopeSeen.find(s => s.slope == slope.slope && s.sign == slope.sign)) === 'undefined')
        {
            count++;
            slopeSeen.push(slope);
        }
    }
    
    return count;
};

Asteroid.prototype.varporisationOrder = function()
{
    let distances = new Map();
    let angles = new Map();
    let sortedroids = [];
    let uniqueangles = new Set();
    console.log(`starting x: ${this.position.x} y: ${this.position.y}`);
    for(let other of this.slopes.keys())
    {       
        let xdiff = other.position.x - this.position.x;
        let ydiff = this.position.y - other.position.y;
               
        let dist = Math.sqrt(xdiff**2 + ydiff**2);
        distances.set(other, dist);

        let angle = Math.acos(ydiff/dist);
        angles.set(other, angle);
        uniqueangles.add(angle);

        sortedroids.push([other, angles.get(other), dist]);
    }

    sortedroids.sort((A, B) =>
                     {
                         if(angles.get(A[0]) < angles.get(B[0]))
                         {
                             return -1;
                         }

                         if(angles.get(A[0]) > angles.get(B[0]))
                         {
                             return 1;
                         }

                         if(angles.get(A[0]) == angles.get(B[0]))
                         {
                             if(distances.get(A[0]) < distances.get(B[0]))
                             {
                                 return -1;
                             }

                             if(distances.get(A[0]) > distances.get(B[0]))
                             {
                                 return 1;
                             }
                         }

                         return 0;
                     });


    let resorted = [];

    let usedangles = new Set();
    
    while(sortedroids.length > 0)
    {
        let delindex = [];
        for(let a of sortedroids)
        {
            let [asteroid, angle, distance] = a;
            if(uniqueangles.has(angle))
            {
                resorted.push(asteroid);
                delindex.push(sortedroids.indexOf(a));
                usedangles.add(angle);
                uniqueangles.delete(angle);
            }
            
            if(uniqueangles.size == 0)
            {
                uniqueangles = new Set(usedangles);
            }
        }
        
        for(let index of delindex)
        {
            sortedroids.splice(index, 1);
        }
    }

    for(let ast of resorted)
    {
        console.log(`${ast.position.x}, ${ast.position.y}, angle: ${angles.get(ast)}, distance: ${distances.get(ast)}`);
    }
    
    return resorted;
}

function Field(input)
{
    this.asteroids = [];
    let rows = input.split('\n');
    for(let ri = 0; ri < rows.length; ri++)
    {
        let row = rows[ri];
        for(let ci = 0; ci < row.length; ci++)
        {
            let c = row[ci];
            if(c === '#')
            {
                let asteroid = new Asteroid({x:ci, y:ri})
                this.asteroids.push(asteroid);
            }
        }
    }
}

Field.prototype.bestAsteroid = function()
{
    for(let asteroid of this.asteroids)
    {
        for(let otherA of this.asteroids)
        {
            if(asteroid === otherA)
            {
                continue;
            }
            asteroid.slopeAndDistance(otherA);
        }
    }

    let bestcount = 0;
    let besteroid = null;
    for(let asteroid of this.asteroids)
    {
        let seecount = asteroid.seeCount();
        if(seecount > bestcount)
        {
            bestcount = seecount;
            besteroid = asteroid;
        }
    }

    return [besteroid, bestcount];
}

Field.prototype.destroy200 = function()
{
    let laserPos = this.bestAsteroid()[0];

    let order = laserPos.varporisationOrder();

    return order[200].position;
}

function testPart1()
{
    let input =`.#..##.###...#######
##.############..##.
.#.######.########.#
.###.#######.####.#.
#####.##.#.##.###.##
..#####..#.#########
####################
#.####....###.#.#.##
##.#################
#####.##.###..####..
..######..##.#######
####.##.####...##..#
.#####..#.######.###
##...#.##########...
#.##########.#######
.####.#.###.###.#.##
....##.##.###..#####
.#.#.###########.###
#.#.#.#####.####.###
###.##.####.##.#..##`;
    let field = new Field(input);
    let result = field.bestAsteroid();
    console.log('expected x: 11, expected y: 13, expected count: 210');
    console.log(`actual   x: ${result[0].position.x}, actual   y: ${result[0].position.y}, actual   count: ${result[1]}`);
    console.log('passed;', result[0].position.x==11 && result[0].position.y==13 && result[1] == 210);
}

function part1()
{
    let input = document.querySelector('pre').innerHTML;
    let field = new Field(input);
    return field.bestAsteroid();
}
    
function testPart2()
{
        let input =`.#..##.###...#######
##.############..##.
.#.######.########.#
.###.#######.####.#.
#####.##.#.##.###.##
..#####..#.#########
####################
#.####....###.#.#.##
##.#################
#####.##.###..####..
..######..##.#######
####.##.####...##..#
.#####..#.######.###
##...#.##########...
#.##########.#######
.####.#.###.###.#.##
....##.##.###..#####
.#.#.###########.###
#.#.#.#####.####.###
###.##.####.##.#..##`;
    let field = new Field(input);
    let result = field.destroy200();
    console.log('expected x: 8, expected y: 2');
    console.log(`actual   x: ${result.x}, actual   y: ${result.y}`);
    console.log('passed;', result.x==8 && result.y==2);
}