152 lines
3.9 KiB
C#
152 lines
3.9 KiB
C#
namespace CeresSearch;
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record Direction(int XOffset, int YOffset)
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{
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public static readonly Direction Up = new(0, -1);
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public static readonly Direction Down = new(0, 1);
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public static readonly Direction Left = new(-1, 0);
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public static readonly Direction Right = new(1, 0);
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public static readonly Direction DownToTheRight = new(1, 1);
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public static readonly Direction DownToTheLeft = new(-1, 1);
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public static readonly Direction UpToTheRight = new(1, -1);
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public static readonly Direction UpToTheLeft = new(-1, -1);
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}
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class Grid(string[] input)
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{
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private readonly Direction[] _directions = [
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Direction.UpToTheLeft,
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Direction.UpToTheRight,
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Direction.DownToTheLeft,
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Direction.DownToTheRight,
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Direction.Up,
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Direction.Down,
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Direction.Left,
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Direction.Right,
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];
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public int CountXmases()
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{
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var total = 0;
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WalkGrid((rowIndex, columnIndex) =>
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{
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if (FoundXmas(rowIndex, columnIndex))
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{
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total++;
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}
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});
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return total;
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}
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public int CountOccurrences(string word)
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{
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var total = 0;
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WalkGrid((rowIndex, columnIndex) =>
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total += _directions.Count(direction => FoundWord(word, direction, rowIndex, columnIndex))
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);
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return total;
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}
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private void WalkGrid(Action<int, int> callback)
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{
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for (var rowIndex = 0; rowIndex < input.Length; rowIndex++)
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{
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var row = input[rowIndex];
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for (var columnIndex = 0; columnIndex < row.Length; columnIndex++)
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{
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callback(rowIndex, columnIndex);
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}
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}
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}
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private bool FoundXmas(int rowIndex, int colIndex)
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{
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var currentCharacter = input[rowIndex][colIndex];
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if (currentCharacter is not 'A')
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{
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return false;
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}
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var xmasMap = new Dictionary<Direction, char>();
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foreach (var direction in _directions)
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{
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if (
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direction == Direction.Up ||
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direction == Direction.Down ||
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direction == Direction.Left ||
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direction == Direction.Right
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)
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{
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continue;
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}
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var rowIndexToCheck = rowIndex + direction.XOffset;
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var colIndexToCheck = colIndex + direction.YOffset;
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if (IsOffGrid(rowIndexToCheck, colIndexToCheck))
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{
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return false;
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}
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var characterToCheck = input[rowIndexToCheck][colIndexToCheck];
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if (characterToCheck != 'S' && characterToCheck != 'M')
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{
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return false;
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}
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xmasMap.Add(direction, characterToCheck);
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}
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return IsValidXmas(xmasMap);
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}
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private static bool IsValidXmas(Dictionary<Direction, char> map)
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{
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var upToTheRight = map[Direction.UpToTheRight];
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var downToTheLeft = map[Direction.DownToTheLeft];
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var upToTheLeft = map[Direction.UpToTheLeft];
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var downToTheRight = map[Direction.DownToTheRight];
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return upToTheRight != downToTheLeft && upToTheLeft != downToTheRight;
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}
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private bool FoundWord(string word, Direction direction, int rowIndex, int columnIndex)
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{
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for (var currentTargetCharacterIndex = 0; currentTargetCharacterIndex < word.Length; currentTargetCharacterIndex++)
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{
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var currentTargetCharacter = word[currentTargetCharacterIndex];
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var currentCharacterRowIndex = rowIndex + (direction.XOffset * currentTargetCharacterIndex);
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var currentCharacterColumnIndex = columnIndex + (direction.YOffset * currentTargetCharacterIndex);
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if (IsOffGrid(currentCharacterRowIndex, currentCharacterColumnIndex))
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{
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return false;
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}
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var currentCharacter = input[currentCharacterRowIndex][currentCharacterColumnIndex];
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if (currentCharacter != currentTargetCharacter)
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{
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return false;
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}
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}
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return true;
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}
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private bool IsOffGrid(int rowIndex, int columnIndex)
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{
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return rowIndex < 0 ||
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rowIndex > input.Length - 1 ||
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columnIndex < 0 ||
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columnIndex > input[0].Length - 1;
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}
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} |