87 lines
3.3 KiB
C#
87 lines
3.3 KiB
C#
using AdvenOfCode.Contracts;
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using AdventOfCode.Extensions;
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using AdventOfCode.HelperClasses;
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using CoordinatePair = (long minX, long minY, long maxX, long maxY);
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namespace AoC_2025;
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public class Day09 : IPuzzleSolver<long>
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{
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private Coordinate[] ParsePuzzleInput(string path)
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{
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var puzzleInput = File.ReadAllLines(path)
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.Where(line => !string.IsNullOrWhiteSpace(line))
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.Select(line => line.Split(',', StringSplitOptions.RemoveEmptyEntries).Select(str => long.Parse(str)).ToArray())
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.Select(numbers => new Coordinate(numbers[0], numbers[1]))
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.ToArray();
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return puzzleInput;
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}
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public long SolvePart1(string pathToPuzzleInput)
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{
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var redTiles = ParsePuzzleInput(pathToPuzzleInput);
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var possibleRectangles = GetAllPossibleRectanglesAsPairs(redTiles);
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var areas = GetOrderedAreas(possibleRectangles);
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return areas.First();
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}
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public long SolvePart2(string pathToPuzzleInput)
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{
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var redTiles = ParsePuzzleInput(pathToPuzzleInput);
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var borders = GetBordersAsPairs(redTiles);
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var possibleRectangles = GetAllPossibleRectanglesAsPairs(redTiles);
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var containedRectangles = GetRectanglesContainedInBorders(possibleRectangles, borders);
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var areas = GetOrderedAreas(containedRectangles);
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return areas.First();
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}
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private IOrderedEnumerable<long> GetOrderedAreas(IEnumerable<CoordinatePair> containedRectangles)
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{
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return containedRectangles
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.Select(rectangle => GetArea(new Coordinate(rectangle.maxX, rectangle.maxY), new Coordinate(rectangle.minX, rectangle.minY)))
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.OrderDescending();
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}
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private IEnumerable<CoordinatePair> GetRectanglesContainedInBorders(IEnumerable<CoordinatePair> possibleRectangles, CoordinatePair[] borders)
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{
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return possibleRectangles
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.Where(rectangle => IsRectangleInsideBorders(borders, rectangle));
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}
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private IEnumerable<CoordinatePair> GetAllPossibleRectanglesAsPairs(Coordinate[] redTiles)
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{
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return redTiles.Combinations(2).Select(x => AsPair(x[0], x[1]));
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}
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private CoordinatePair[] GetBordersAsPairs(Coordinate[] redTiles)
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{
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return GetBorders(redTiles).Select(x => AsPair(x.a, x.b)).ToArray();
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}
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private bool IsRectangleInsideBorders(CoordinatePair[] borders, CoordinatePair rectangle)
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{
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var bordersCrossed = borders.Any(border => RectangleCrossesBorder(rectangle, border));
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return !bordersCrossed;
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}
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private CoordinatePair AsPair(Coordinate a, Coordinate b)
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{
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return (Math.Min(a.X, b.X), Math.Min(a.Y, b.Y), Math.Max(a.X, b.X), Math.Max(a.Y, b.Y));
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}
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private bool RectangleCrossesBorder(CoordinatePair rectangle, CoordinatePair borderSegment)
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{
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return rectangle.minX < borderSegment.maxX && rectangle.minY < borderSegment.maxY &&
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rectangle.maxX > borderSegment.minX && rectangle.maxY > borderSegment.minY;
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}
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private long GetArea(Coordinate tileA, Coordinate tileB)
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{
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return (Math.Abs(tileA.X - tileB.X) + 1) * (Math.Abs(tileA.Y - tileB.Y) + 1);
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}
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private IEnumerable<(Coordinate a, Coordinate b)> GetBorders(Coordinate[] tiles)
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{
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return tiles.Zip([..tiles[1..], tiles[0]], (a, b) => (a, b));
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}
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} |