112 lines
3.9 KiB
C#
112 lines
3.9 KiB
C#
namespace AOC2020;
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/// <summary>
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/// Day 17: <a href="https://adventofcode.com/2020/day/17" />
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/// </summary>
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public sealed class Day17() : Day(2020, 17, "Conway Cubes")
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{
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private readonly Dictionary<(int x, int y, int z), char> _plane = [];
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private readonly Dictionary<(int x, int y, int z, int w), char> _plane4 = [];
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public override void ProcessInput()
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{
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var input = Input.ToList();
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for (var x = 0; x < 32; x++)
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for (var y = 0; y < 32; y++)
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for (var z = 0; z < 32; z++)
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_plane[(x, y, z)] = '.';
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for (var x = 0; x < 32; x++)
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for (var y = 0; y < 32; y++)
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for (var z = 0; z < 32; z++)
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for (var w = 0; w < 32; w++)
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_plane4[(x, y, z, w)] = '.';
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for (var y = 0; y < input.Count; y++)
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for (var x = 0; x < input[y].Length; x++)
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_plane[(x, y, 0)] = input[y][x];
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for (var y = 0; y < input.Count; y++)
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for (var x = 0; x < input[y].Length; x++)
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_plane4[(x, y, 0, 0)] = input[y][x];
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}
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private static int Neighbors(IReadOnlyDictionary<(int x, int y, int z), char> plane, int x, int y, int z)
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{
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var neighbors = 0;
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foreach (var i in new[] { -1, 0, 1 })
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foreach (var j in new[] { -1, 0, 1 })
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foreach (var k in new[] { -1, 0, 1 })
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{
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if (i == 0 && j == 0 && k == 0) continue;
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if (plane[((x + i) & 31, (y + j) & 31, (z + k) & 31)] == '#') neighbors++;
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}
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return neighbors;
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}
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private static Dictionary<(int x, int y, int z), char> Iterate(
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IReadOnlyDictionary<(int x, int y, int z), char> prev)
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{
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var next = new Dictionary<(int x, int y, int z), char>();
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for (var z = 0; z < 32; z++)
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for (var y = 0; y < 32; y++)
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for (var x = 0; x < 32; x++)
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{
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var active = Neighbors(prev, x, y, z);
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if (prev[(x, y, z)] == '#')
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next[(x, y, z)] = active is 2 or 3 ? '#' : '.';
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else
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next[(x, y, z)] = active == 3 ? '#' : '.';
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}
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return next;
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}
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private static int Neighbors4(IReadOnlyDictionary<(int x, int y, int z, int w), char> plane, int x, int y,
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int z, int w)
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{
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var neighbors = 0;
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foreach (var i in new[] { -1, 0, 1 })
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foreach (var j in new[] { -1, 0, 1 })
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foreach (var k in new[] { -1, 0, 1 })
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foreach (var l in new[] { -1, 0, 1 })
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{
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if (i == 0 && j == 0 && k == 0 && l == 0) continue;
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if (plane[((x + i) & 31, (y + j) & 31, (z + k) & 31, (w + l) & 31)] == '#') neighbors++;
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}
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return neighbors;
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}
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private static Dictionary<(int x, int y, int z, int w), char> Iterate4(
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IReadOnlyDictionary<(int x, int y, int z, int w), char> prev)
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{
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var next = new Dictionary<(int x, int y, int z, int w), char>();
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for (var z = 0; z < 32; z++)
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for (var y = 0; y < 32; y++)
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for (var x = 0; x < 32; x++)
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for (var w = 0; w < 32; w++)
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{
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var active = Neighbors4(prev, x, y, z, w);
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if (prev[(x, y, z, w)] == '#')
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next[(x, y, z, w)] = active is 2 or 3 ? '#' : '.';
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else
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next[(x, y, z, w)] = active == 3 ? '#' : '.';
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}
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return next;
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}
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public override object Part1() =>
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Enumerable.Range(0, 6).Aggregate(_plane, (current, _) => Iterate(current)).Values.Count(v => v == '#');
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public override object Part2() =>
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Enumerable.Range(0, 6).Aggregate(_plane4, (current, _) => Iterate4(current)).Values.Count(v => v == '#');
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}
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