benharri.org
my advent of code solutions
2024 day 4 part 2
+30
-12
+28
-10
Solutions/2024/Day04.cs
+28
-10
Solutions/2024/Day04.cs
···
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5
/// </summary>
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public sealed class Day04() : Day(2024, 4, "Ceres Search")
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{
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private char[][] _grid = [];
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+
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private static readonly List<(int dx, int dy)> Directions =
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[
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(-1, -1), (-1, 0), (-1, 1),
···
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(1, -1), (1, 0), (1, 1),
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];
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private static bool OutOfBounds(char[][] grid, int x, int y) =>
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x < 0 || x >= grid[0].Length || y < 0 || y >= grid.Length;
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public override void ProcessInput() => _grid = Input.Select(line => line.ToArray()).ToArray();
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public override object Part1()
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{
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var grid = Input.Select(line => line.ToArray()).ToArray();
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var count = 0;
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for (var y = 0; y < grid.Length; y++)
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for (var x = 0; x < grid[0].Length; x++)
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if (grid[y][x] == 'X')
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for (var y = 0; y < _grid.Length; y++)
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for (var x = 0; x < _grid[0].Length; x++)
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if (_grid[y][x] == 'X')
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{
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foreach (var (dx, dy) in Directions)
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{
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int magnitude = 1, newY = y + dy, newX = x + dx;
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if (OutOfBounds(grid, newX, newY)) continue;
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if (OutOfBounds(_grid, newX, newY)) continue;
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-
while (grid[newY][newX] == "XMAS"[magnitude])
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while (_grid[newY][newX] == "XMAS"[magnitude])
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{
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if (++magnitude > 3)
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{
···
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newY += dy;
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newX += dx;
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if (OutOfBounds(grid, newX, newY)) break;
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if (OutOfBounds(_grid, newX, newY)) break;
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}
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}
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}
···
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return count;
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}
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-
private static bool OutOfBounds(char[][] grid, int x, int y) =>
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x < 0 || x >= grid[0].Length || y < 0 || y >= grid.Length;
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+
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public override object Part2()
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{
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var count = 0;
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+
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for (var y = 1; y < _grid.Length - 1; y++)
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for (var x = 1; x < _grid[0].Length - 1; x++)
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if (_grid[y][x] == 'A')
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if (((_grid[y - 1][x - 1] == 'M' && _grid[y + 1][x + 1] == 'S')
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|| (_grid[y - 1][x - 1] == 'S' && _grid[y + 1][x + 1] == 'M'))
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&& ((_grid[y + 1][x - 1] == 'M' && _grid[y - 1][x + 1] == 'S')
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|| (_grid[y + 1][x - 1] == 'S' && _grid[y - 1][x + 1] == 'M')))
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count++;
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-
public override object Part2() => "";
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return count;
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}
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}
+2
-2
Tests/Test2024.cs
+2
-2
Tests/Test2024.cs
···
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8
[DataRow(typeof(Day01), "1319616", "27267728")]
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[DataRow(typeof(Day02), "321", "386")]
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[DataRow(typeof(Day03), "163931492", "76911921")]
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[DataRow(typeof(Day04), "2573", "")]
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+
[DataRow(typeof(Day04), "2573", "1850")]
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public void CheckAllDays(Type dayType, string part1, string part2) =>
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Common.CheckDay(dayType, part1, part2);
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···
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[DataRow(typeof(Day01), "11", "31")]
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[DataRow(typeof(Day02), "2", "4")]
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[DataRow(typeof(Day03), "161", "48")]
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[DataRow(typeof(Day04), "18", "")]
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[DataRow(typeof(Day04), "18", "9")]
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public void CheckTestInputs(Type dayType, string part1, string part2) =>
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Common.CheckDay(dayType, part1, part2, true);
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}