[2022] Day9 added
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@ -2,6 +2,16 @@ namespace AdventOfCode.Utils;
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public static class Extensions
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{
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public static int Signal(this int x)
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{
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return x switch
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{
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< 0 => -1,
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> 0 => 1,
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_ => 0
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};
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}
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/// <summary>
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/// Returns a slice of the given list
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/// </summary>
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@ -76,4 +86,24 @@ public static class Extensions
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ret.Add(entry.Key, entry.Value.Clone());
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return ret;
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}
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public static void Fill<T>(this List<T> list, int count, T element)
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where T : ICloneable
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{
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for (int i = 0; i < count; i++)
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list.Add(element);
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}
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public static void Fill<T>(this List<List<T>> list, int count, List<T> element)
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{
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for (int i = 0; i < count; i++)
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list.Add(element.Clone());
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}
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public static void Set<T>(this List<T> list, int index, T element)
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{
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List<T> backup = list.Clone();
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list.Clear();
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for (int i = 0; i < list.Count; i++) list.Add(i == index ? element : list[i]);
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}
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}
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126
Year2022/Day9.cs
126
Year2022/Day9.cs
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@ -1,87 +1,99 @@
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using AdventOfCode.Utils;
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namespace AdventOfCode.Year2022;
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public class Day9
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{
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private static readonly List<(char, int)> Moves = new();
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private static readonly Dictionary<char, List<int>> Position = new()
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{
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['H'] = new List<int>(),
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['T'] = new List<int>()
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};
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public Day9()
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{
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Console.WriteLine("Day9 Solution");
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List<(char, int)> moves = new List<(char, int)>();
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File.ReadAllLines("inputs/day9.txt").ToList().ForEach(line =>
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{
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string[] split = line.Split(" ");
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Moves.Add((Convert.ToChar(split[0]), Convert.ToInt32(split[1])));
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moves.Add((Convert.ToChar(split[0]), Convert.ToInt32(split[1])));
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});
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Console.WriteLine($"Part1 Result: {Part1()}");
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Console.WriteLine($"Part2 Result: {Part2()}");
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Console.WriteLine($"Part1 Result: {GetPositionCount(moves, 2)}");
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Console.WriteLine($"Part2 Result: {GetPositionCount(moves, 10)}");
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Console.WriteLine("\n=============================\n");
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}
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private static int Part1()
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private static int GetPositionCount(List<(char, int)> moves, int knots)
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{
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Position['H'] = new[] {0, 0}.ToList();
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Position['T'] = new[] {0, 0}.ToList();
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HashSet<(int, int)> usedPositions = new HashSet<(int, int)>();
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List<List<int>> currentPositions = new List<List<int>>();
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currentPositions.Fill(knots, new List<int>(new[]{0,0}));
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HashSet<(int, int)> tailHistory = new HashSet<(int, int)>();
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foreach ((char, int) move in Moves)
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foreach ((char, int) move in moves)
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for (int moveN = 0; moveN < move.Item2; moveN++)
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{
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List<int> head = Position['H'];
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List<int> tail = Position['T'];
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for (int i = 0; i < move.Item2; i++)
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int[] vector = GetVector(move.Item1);
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int[] previousTailPosition = currentPositions[0].ToArray();
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currentPositions[0] = UpdateHead(vector, currentPositions[0]);
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for (int tailN = 0; tailN < knots-1; tailN++)
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{
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if (move.Item1 == 'U')
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{
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head[1]++;
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if (ValidatePosition()) continue;
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tail[1]++;
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tail[0] += head[0] - tail[0];
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int[] nextPreviousTailPosition = currentPositions[tailN + 1].ToArray();
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currentPositions[tailN + 1] = UpdateTail(currentPositions[tailN], currentPositions[tailN + 1], previousTailPosition);
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previousTailPosition = nextPreviousTailPosition;
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if (tailN == knots - 2)
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tailHistory.Add((currentPositions[knots - 1][0], currentPositions[knots - 1][1]));
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}
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else if (move.Item1 == 'D')
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{
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head[1]--;
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if (ValidatePosition()) continue;
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tail[1]--;
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tail[0] += head[0] - tail[0];
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}
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else if (move.Item1 == 'R')
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{
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head[0]++;
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if (ValidatePosition()) continue;
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tail[0]++;
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tail[1] += head[1] - tail[1];
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}
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else if (move.Item1 == 'L')
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{
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head[0]--;
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if (ValidatePosition()) continue;
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tail[0]--;
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tail[1] += head[1] - tail[1];
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}
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usedPositions.Add((tail[0], tail[1]));
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}
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}
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return usedPositions.Count;
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}
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private static int Part2()
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return tailHistory.Count;
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}
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private static List<int> UpdateHead(int[] vector, List<int> currentPosition)
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{
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Position['H'] = new[] {0, 0}.ToList();
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Position['T'] = new[] {0, 0}.ToList();
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HashSet<(int, int)> usedPositions = new HashSet<(int, int)>();
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currentPosition[0] += vector[0];
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currentPosition[1] += vector[1];
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return new List<int> { currentPosition[0], currentPosition[1] };
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}
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foreach ((char, int) move in Moves)
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private static List<int> UpdateTail(List<int> currentHeadPosition, List<int> currentTailPosition, int[] previousTailPosition)
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{
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List<int> head = new List<int>
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{
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currentHeadPosition[0] - previousTailPosition[0],
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currentHeadPosition[1] - previousTailPosition[1]
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};
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if (Math.Abs(currentHeadPosition[0] - currentTailPosition[0]) > 1 ||
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Math.Abs(currentHeadPosition[1] - currentTailPosition[1]) > 1)
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{
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if (previousTailPosition[0] == currentTailPosition[0] ||
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previousTailPosition[1] == currentTailPosition[1])
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return new List<int>
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{
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currentTailPosition[0] + head[0],
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currentTailPosition[1] + head[1]
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};
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List<int> difference = new List<int>
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{
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currentHeadPosition[0] - currentTailPosition[0],
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currentHeadPosition[1] - currentTailPosition[1]
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};
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return new List<int>
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{
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currentTailPosition[0] + difference[0].Signal() * Math.Min(Math.Abs(difference[0]), 1),
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currentTailPosition[1] + difference[1].Signal() * Math.Min(Math.Abs(difference[1]), 1)
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};
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}
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return usedPositions.Count;
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return currentTailPosition;
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}
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private static bool ValidatePosition()
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=> Position['H'][0] - Position['T'][0] is > -2 and < 2 && Position['H'][1] - Position['T'][1] is > -2 and < 2;
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private static int[] GetVector(char direction)
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{
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return direction switch
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{
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'U' => new[] { 1, 0 },
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'D' => new[] { -1, 0 },
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'R' => new[] { 0, 1 },
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'L' => new[] { 0, -1 },
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_ => new[] { 0, 0 }
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};
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}
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}
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