It's no use; your navigation system simply isn't capable of providing walking directions in the arctic circle, and certainly not in 1018.

The Elves suggest an alternative. In times like these, North Pole rescue operations will arrange points of light in the sky to guide missing Elves back to base. Unfortunately, the message is easy to miss: the points move slowly enough that it takes hours to align them, but have so much momentum that they only stay aligned for a second. If you blink at the wrong time, it might be hours before another message appears.

Read the full puzzle.

using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCode.Y2018.Day10;

[ProblemName("The Stars Align")]
class Solution : Solver {

    public object PartOne(string input) => Solver(input).st.Ocr();

    public object PartTwo(string input) => Solver(input).seconds;

    (string st, int seconds) Solver(string input) {
        // position=< 21992, -10766> velocity=<-2,  1>
        var rx = new Regex(@"position=\<\s*(?<x>-?\d+),\s*(?<y>-?\d+)\> velocity=\<\s*(?<vx>-?\d+),\s*(?<vy>-?\d+)\>");
        var points = (
            from line in input.Split("\n")
            let m = rx.Match(line)
            select new Point {
                x = int.Parse(m.Groups["x"].Value),
                y = int.Parse(m.Groups["y"].Value),
                vx = int.Parse(m.Groups["vx"].Value),
                vy = int.Parse(m.Groups["vy"].Value)
            }
        ).ToArray();

        var seconds = 0;
        Func<bool, (int left, int top, long width, long height)> step = (bool forward) => {
            foreach (var point in points) {
                if (forward) {
                    point.x += point.vx;
                    point.y += point.vy;
                } else {
                    point.x -= point.vx;
                    point.y -= point.vy;
                }
            }
            seconds += forward ? 1 : -1;

            var minX = points.Min(pt => pt.x);
            var maxX = points.Max(pt => pt.x);
            var minY = points.Min(pt => pt.y);
            var maxY = points.Max(pt => pt.y);
            return (minX, minY, maxX - minX + 1, maxY - minY + 1);
        };

        var area = long.MaxValue;
        while (true) {

            var rect = step(true);
            var areaNew = (rect.width) * (rect.height);

            if (areaNew > area) {
                rect = step(false);
                var st = "";
                for(var irow=0;irow<rect.height;irow++){

                    for(var icol=0;icol<rect.width;icol++){
                        st += points.Any(p => p.x - rect.left == icol && p.y-rect.top == irow) ? '#': ' ';
                    }
                    st+= "\n";
                }
                return (st, seconds);
            }
            area = areaNew;
        }
    }
}

class Point {
    public int x;
    public int y;
    public int vx;
    public int vy;
}

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