98 lines
2.6 KiB
C#
98 lines
2.6 KiB
C#
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var lines = File.ReadAllLines("input.txt");
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var charArray = new char[lines.Length, lines[0].Length];
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for (var i = 0; i < charArray.GetLength(0); i++)
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for (var j = 0; j < charArray.GetLength(1); j++)
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{
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charArray[i, j] = lines[i][j];
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}
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Console.WriteLine($"Part1: {FindXmas(charArray)}\nPart2: {FindMas(charArray)}");
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int FindMas(char[,] grid)
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{
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var rows = grid.GetLength(0);
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var cols = grid.GetLength(1);
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var directions = new[,]
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{
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{ -1, 1 }, // diagonal up right
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{ 1, 1 }, // diagonal down right
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{ -1, -1 }, // diagonal up left
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{ 1, -1 } // diagonal down left
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};
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List<string> masCenterCoordinates = new();
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for (var r = 0; r < rows; r++)
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{
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for (var c = 0; c < cols; c++)
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{
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for (var d = 0; d < directions.GetLength(0); d++)
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{
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var masCoordinates = CheckWord(r, c, directions[d, 0], directions[d, 1], grid, "MAS");
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if (masCoordinates != null)
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{
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masCenterCoordinates.Add($"{masCoordinates[1][0]},{masCoordinates[1][1]}");
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}
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}
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}
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}
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var masCountDict = masCenterCoordinates.GroupBy(item => item).ToDictionary(group => group.Key, group => group.Count()).Where(x => x.Value > 1);
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return masCountDict.Count();
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}
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int FindXmas(char[,] grid)
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{
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var rows = grid.GetLength(0);
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var cols = grid.GetLength(1);
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var xmasCount = 0;
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var directions = new[,]
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{
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{ -1, 0 }, // up
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{ 0, 1 }, // right
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{ 0, -1 }, // left
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{ 1, 0 }, // down
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{ -1, 1 }, // diagonal up right
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{ 1, 1 }, // diagonal down right
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{ -1, -1 }, // diagonal up left
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{ 1, -1 } // diagonal down left
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};
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for (var r = 0; r < rows; r++)
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{
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for (var c = 0; c < cols; c++)
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{
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for (var d = 0; d < directions.GetLength(0); d++)
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{
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if (CheckWord(r, c, directions[d, 0], directions[d, 1], grid, "XMAS") != null)
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{
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xmasCount++;
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}
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}
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}
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}
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return xmasCount;
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}
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List<int[]>? CheckWord(int r, int c, int dr, int dc, char[,] grid, string word)
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{
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var characterCoordinates = new List<int[]>();
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for (var i = 0; i < word.Length; i++)
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{
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var newR = r + i * dr;
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var newC = c + i * dc;
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if (!IsValid(newR, newC, grid) || grid[newR, newC] != word[i]) return null;
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characterCoordinates.Add([newR, newC]);
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}
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return characterCoordinates;
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}
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bool IsValid(int r, int c, char[,] grid) => r >= 0 && r < grid.GetLength(0) && c >= 0 && c < grid.GetLength(1);
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