105 lines
4.7 KiB
C#
105 lines
4.7 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Reflection.Emit;
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using System.Text;
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using System.Threading.Tasks;
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using System.Text.RegularExpressions;
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namespace Advent24
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{
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internal class Day8
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{
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public Day8()
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{
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String fileData = System.IO.File.ReadAllText(@"..\..\..\inputd8.txt");
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// set this to false for part 1
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Boolean enableResonantHarmonics = true;
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// get width of line to be able to navigate the map block in
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// both dimensions
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Int32 mapWidth = fileData.IndexOf('\n');
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Int32 mapWidthIncludingNewline = mapWidth + 1;
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String pattern = @"[A-Za-z0-9]";
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Regex r = new(pattern, RegexOptions.Multiline, TimeSpan.FromMilliseconds(150));
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Match m = r.Match(fileData);
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// list of linear-integer locations of antennas indexed by antenna type (a single alphanumeric character)
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Dictionary<Char, List<Int32>> antennaLocationsMap = [];
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while (m.Success)
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{
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if (!antennaLocationsMap.TryGetValue(m.Groups[0].Value[0], out List<int>? antennaLocations))
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antennaLocationsMap.Add(m.Groups[0].Value[0], [m.Groups[0].Index]);
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else
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antennaLocationsMap[m.Groups[0].Value[0]].Add(m.Groups[0].Index);
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// Console.WriteLine("antennaLocationsMap[{0:d}] = {1:d}", m.Groups[0].Value[0], antennaLocationsMap[m.Groups[0].Value[0]].Last());
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m = m.NextMatch();
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}
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// set of linear-integer locations of antinodes indexed by antenna type (single-character alphanumeric)
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Dictionary<Char, HashSet<Int32>> antinodeLocationsMap = [];
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// set of linear-integer locations of antinodes overall
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HashSet<Int32> overallAntinodeLocations = [];
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foreach (Char antennaType in antennaLocationsMap.Keys)
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{
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if (!antinodeLocationsMap.TryGetValue(antennaType, out HashSet<int>? antinodeLocations))
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antinodeLocationsMap.Add(antennaType, []);
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// for each (ordered) pair of antennaLocations of the same antenna type, we'll construct an antinode
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// and then add it to the antinodeLocationsMap (keyed by antenna type)
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foreach(Int32 antennaLocation1 in antennaLocationsMap[antennaType])
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foreach(Int32 antennaLocation2 in antennaLocationsMap[antennaType])
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{
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if (antennaLocation1 == antennaLocation2)
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continue;
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Int32 antennaLocationDifference = antennaLocation2 - antennaLocation1;
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Int32 antennaLocationXDifference = (antennaLocation2 % mapWidthIncludingNewline) - (antennaLocation1 % mapWidthIncludingNewline);
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Int32 antinodeLocation = antennaLocation2;
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do
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{
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Int32 antinodePreviousLocationX = antinodeLocation % mapWidthIncludingNewline;
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antinodeLocation += antennaLocationDifference;
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Int32 antinodeLocationXDifference = (antinodeLocation % mapWidthIncludingNewline) - antinodePreviousLocationX;
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// bounds checking
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if (
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antinodeLocation < 0 ||
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antinodeLocation >= fileData.Length ||
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fileData[antinodeLocation] == '\n' ||
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// x-direction having changed implies we crossed the right/left boundary
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((antennaLocationXDifference > 0) != (antinodeLocationXDifference > 0))
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)
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break;
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antinodeLocationsMap[antennaType].Add(antinodeLocation);
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} while (enableResonantHarmonics);
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if(enableResonantHarmonics)
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{
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antinodeLocationsMap[antennaType].Add(antennaLocation1);
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antinodeLocationsMap[antennaType].Add(antennaLocation2);
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}
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}
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// adding to the overall antinode location set
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overallAntinodeLocations = [.. overallAntinodeLocations, .. antinodeLocationsMap[antennaType]];
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}
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Int32 numberOfUniqueAntinodeLocations = overallAntinodeLocations.Count;
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Console.WriteLine("numberOfUniqueAntinodeLocations = {0:d}", numberOfUniqueAntinodeLocations);
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// to keep the console window from closing
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Console.ReadKey();
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}
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}
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}
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