53 lines
1.5 KiB
C#
53 lines
1.5 KiB
C#
namespace AOC2019;
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public sealed class Day03 : Day
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{
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private readonly IEnumerable<(int, int)> _intersections;
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private readonly List<Dictionary<(int, int), int>> _wires;
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public Day03() : base(2019, 3, "Crossed Wires")
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{
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_wires = Input.Select(ParseWire).ToList();
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_intersections = _wires[0].Keys.Intersect(_wires[1].Keys);
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}
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public override string Part1()
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{
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return $"{_intersections.Min(x => Math.Abs(x.Item1) + Math.Abs(x.Item2))}";
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}
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public override string Part2()
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{
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// add 2 to count (0, 0) on both lines
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return $"{_intersections.Min(x => _wires[0][x] + _wires[1][x]) + 2}";
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}
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private static Dictionary<(int, int), int> ParseWire(string line)
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{
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var r = new Dictionary<(int, int), int>();
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int x = 0, y = 0, c = 0;
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foreach (var step in line.Split(','))
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{
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int i = 0, d = int.Parse(step[1..]);
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switch (step[0])
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{
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case 'U':
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for (; i < d; i++) r.TryAdd((x, ++y), c++);
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break;
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case 'D':
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for (; i < d; i++) r.TryAdd((x, --y), c++);
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break;
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case 'R':
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for (; i < d; i++) r.TryAdd((++x, y), c++);
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break;
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case 'L':
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for (; i < d; i++) r.TryAdd((--x, y), c++);
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break;
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}
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}
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return r;
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}
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}
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