Run with example input here

$ p=0,4 v=3,-3
$ p=6,3 v=-1,-3
$ p=10,3 v=-1,2
$ p=2,0 v=2,-1
$ p=0,0 v=1,3
$ p=3,0 v=-2,-2
$ p=7,6 v=-1,-3
$ p=3,0 v=-1,-2
$ p=9,3 v=2,3
$ p=7,3 v=-1,2
$ p=2,4 v=2,-3
$ p=9,5 v=-3,-3
.
PartOne ← (
  # &rs ∞ &fo "input-14.txt"
  ⊜(↯2_2⋕regex"-?\\d+")≠@\n.
  ≡(⍜⌵(◿11_7)+°⊟⍜⊡₁×₁₀₀)
  ↯⟜(▽×°⊟)7_11 0
  ⍜↙₃(⍜≡↙₅+₁⍜≡↘₆+₂)
  ⍜↘₄(⍜≡↙₅+₃⍜≡↘₆+₄)
  /×≡◇⧻⊕□-₁⊸(⊡:)⍉
)

PartTwo ← (
  # &rs ∞ &fo "input-14.txt"
  ⊜(↯2_2⋕regex"-?\\d+")≠@\n.
  0 # number of seconds to start at
  0_0
  ⍢(◡(≡(⍜⌵(◿11_7)+°⊟⍜⊡₁×):)◌
    ◿[11_7]≡+[11_7]
    ⊙+₁
  | ≠⊙(⧻◴)⧻.)
  ⊙◌◌
  -₁
)

&p "Day 14:"
&pf "Part 1: "
&p PartOne
&pf "Part 2: "
&p PartTwo

1. Open the uiua pad with code here
2. Replace the 0 in the first line with your solution for part two
3. If necessary, change the name of the file containing your input
4. Drag a file containing your input onto the pad to upload it and run the code
5. An image should be displayed

import fs from "fs";

type Coord = {x: number, y: number};
type Robot = {start: Coord, velocity: Coord};

const SIZE: Coord = {x: 101, y: 103};

const input: Robot[] = fs.readFileSync("./14/input.txt", "utf-8")
    .split(/[\r\n]+/)
    .map(row => /p=(-?\d+),(-?\d+)\sv=(-?\d+),(-?\d+)/.exec(row))
    .filter(matcher => matcher != null)
    .map(matcher => {
        return {
            start: {x: parseInt(matcher[1]), y: parseInt(matcher[2])},
            velocity: {x: parseInt(matcher[3]), y: parseInt(matcher[4])}
        };
    });

console.info("Part 1: " + safetyFactor(input.map(robot => calculatePosition(robot, SIZE, 100)), SIZE));

// Part 2
// Turns out the Christmas tree is arranged the first time none of the robots are overlapping
for (let i = 101; true; i++) {
    const positions = input.map(robot => calculatePosition(robot, SIZE, i));
    if (positions.every((position, index, arr) => arr.findIndex(pos => pos.x === position.x && pos.y === position.y) === index)) {
        console.info("Part 2: " + i);
        break;
    }
}

function calculatePosition(robot: Robot, size: Coord, seconds: number): Coord {
    return {
        x: ((robot.start.x + robot.velocity.x * seconds) % size.x + size.x) % size.x,
        y: ((robot.start.y + robot.velocity.y * seconds) % size.y + size.y) % size.y
    };
}

function safetyFactor(positions: Coord[], size: Coord): number {
    const midX = Math.floor(size.x / 2);
    const midY = Math.floor(size.y / 2);

    let quadrant0 = 0; // Top-left
    let quadrant1 = 0; // Top-right
    let quadrant2 = 0; // Bottom-left
    let quadrant3 = 0; // Bottom-right

    for (const {x,y} of positions) {
        if (x === midX || y === midY) { continue; }

        if (x < midX && y < midY) { quadrant0++; }
        else if (x > midX && y < midY) { quadrant1++; }
        else if (x < midX && y > midY) { quadrant2++; }
        else if (x > midX && y > midY) { quadrant3++; }
    }

    return quadrant0 * quadrant1 * quadrant2 * quadrant3;
}

#include "common.h"

#define SAMPLE 0
#define GW (SAMPLE ? 11 : 101)
#define GH (SAMPLE ?  7 : 103)
#define NR 501

int
main(int argc, char **argv)
{
	static char g[GH][GW];
	static int px[NR],py[NR], vx[NR],vy[NR];

	int p1=0, n=0, sec, i, x,y, q[4]={}, run;

	if (argc > 1)
		DISCARD(freopen(argv[1], "r", stdin));

	for (; scanf(" p=%d,%d v=%d,%d", px+n,py+n, vx+n,vy+n)==4; n++)
		assert(n+1 < NR);

	for (sec=1; !SAMPLE || sec <= 100; sec++) {
		memset(g, 0, sizeof(g));
		memset(q, 0, sizeof(q));

		for (i=0; i<n; i++) {
			px[i] = (px[i] + vx[i] + GW) % GW;
			py[i] = (py[i] + vy[i] + GH) % GH;

			g[py[i]][px[i]] = 1;

			if (sec == 100) {
				if (px[i] < GW/2) {
					if (py[i] < GH/2) q[0]++; else
					if (py[i] > GH/2) q[1]++;
				} else if (px[i] > GW/2) {
					if (py[i] < GH/2) q[2]++; else
					if (py[i] > GH/2) q[3]++;
				}
			}
		}

		if (sec == 100)
			p1 = q[0]*q[1]*q[2]*q[3];

		for (y=0; y<GH; y++)
		for (x=0, run=0; x<GW; x++)
			if (!g[y][x])
				run = 0;
			else if (++run >= 10)
				goto found_p2;
	}

found_p2:
	printf("14: %d %d\n", p1, sec);
	return 0;
}

import Data.Maybe
import Text.ParserCombinators.ReadP
import qualified Data.Map.Strict as M

type Coord = (Int, Int)
type Robot = (Coord, Coord)

int :: ReadP Int
int = fmap read $ many1 $ choice $ map char $ '-' : ['0' .. '9']

coord :: ReadP Coord
coord = (,) <$> int <*> (char ',' *> int)

robot :: ReadP Robot
robot = (,) <$> (string "p=" *> coord) <*> (string " v=" *> coord)

robots :: ReadP [Robot]
robots = sepBy robot (char '\n')

simulate :: Coord -> Int -> Robot -> Coord
simulate (x0, y0) t ((x, y), (vx, vy)) =
    ((x + t * vx) `mod` x0, (y + t * vy) `mod` y0)

quadrant :: Coord -> Coord -> Maybe Int
quadrant (x0, y0) (x, y) = case (compare (2*x + 1) x0, compare (2*y + 1) y0) of
    (LT, LT) -> Just 0
    (LT, GT) -> Just 1
    (GT, LT) -> Just 2
    (GT, GT) -> Just 3
    _        -> Nothing

freqs :: (Foldable t, Ord a) => t a -> M.Map a Int
freqs = foldr (\x -> M.insertWith (+) x 1) M.empty

solve :: Coord -> Int -> [Robot] -> Int
solve grid t = product . freqs . catMaybes . map (quadrant grid . simulate grid t)

showGrid :: Coord -> [Coord] -> String
showGrid (x0, y0) cs = unlines
    [ [if (x, y) `M.member` m then '#' else ' ' | x <- [0 .. x0]]
    | let m = M.fromList [(c, ()) | c <- cs]
    , y <- [0 .. y0]
    ]

main :: IO ()
main = do
    rs <- fst . last . readP_to_S robots <$> getContents
    let g = (101, 103)
    print $ solve g 100 rs
    sequence_
        [ writeFile ("tree_" ++ show t) $ showGrid g $ map (simulate g t) rs
        | t <- [0 .. 10000]
        ]