110 lines
3.3 KiB
C#
110 lines
3.3 KiB
C#
namespace AOC2020;
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/// <summary>
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/// Day 14: <a href="https://adventofcode.com/2020/day/14" />
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/// </summary>
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public sealed class Day14() : Day(2020, 14, "Docking Data")
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{
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public override void ProcessInput()
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{
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}
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private static readonly char[] SquareBrackets = ['[', ']'];
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private static readonly char[] BracketsAndEquals = [..SquareBrackets, '='];
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public override object Part1()
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{
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var writes = new Dictionary<ulong, ulong>();
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ulong mask = 0, bits = 0;
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foreach (var line in Input)
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if (line.StartsWith("mask = "))
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{
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var str = line.Split("mask = ", 2)[1];
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mask = bits = 0;
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for (var i = 35; i >= 0; --i)
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switch (str[35 - i])
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{
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case 'X':
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mask |= 1UL << i;
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break;
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case '1':
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bits |= 1UL << i;
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break;
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}
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}
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else
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{
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var spl = line.Split(BracketsAndEquals,
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StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
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.Skip(1)
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.Select(ulong.Parse)
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.ToArray();
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writes[spl[0]] = (spl[1] & mask) | bits;
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}
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return writes.Aggregate<KeyValuePair<ulong, ulong>, ulong>(0, (current, w) => current + w.Value);
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}
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public override object Part2()
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{
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var memory = new Dictionary<ulong, ulong>();
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var mask = "";
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foreach (var line in Input)
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{
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var spl = line.Split(' ', 3, StringSplitOptions.TrimEntries);
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if (spl[0] == "mask")
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{
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mask = spl[2];
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}
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else
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{
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var value = ulong.Parse(spl[2]);
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var addr = ulong.Parse(spl[0].Split(SquareBrackets,
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StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)[1]);
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var floats = new List<int>();
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for (var i = 0; i < mask.Length; i++)
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switch (mask[i])
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{
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case 'X':
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floats.Add(i);
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break;
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case '1':
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addr |= 1UL << (35 - i);
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break;
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}
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if (floats.Count != 0)
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{
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var combos = new List<ulong> { addr };
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foreach (var i in floats)
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{
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var newCombos = new List<ulong>();
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foreach (var c in combos)
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{
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newCombos.Add(c | (1UL << (35 - i)));
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newCombos.Add(c & ~(1UL << (35 - i)));
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}
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combos = newCombos;
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}
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foreach (var c in combos)
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memory[c] = value;
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}
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else
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{
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memory[addr] = value;
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}
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}
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}
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return memory.Aggregate<KeyValuePair<ulong, ulong>, ulong>(0, (current, w) => current + w.Value);
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}
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}
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