using System.Text.RegularExpressions; public enum ConnectWinner { White, Black, None } public class Connect { private enum Cell { Empty, White, Black } private readonly Cell[][] board; public Connect(string[] input) { board = ParseBoard(input); } private static Cell CharToCell(char c) { switch (c) { case 'O': return Cell.White; case 'X': return Cell.Black; default: return Cell.Empty; } } private static Cell[][] ParseBoard(string[] input) { var rows = input.Length; var cols = input[0].Length; var filtered = new List(); foreach (var str in input) { filtered.Add(Regex.Replace(str, @"\s+", "")); } return filtered.Select(row => row.Select(CharToCell).ToArray()).ToArray(); } private int Cols => board[0].Length; private int Rows => board.Length; private bool IsValidCoordinate(Tuple coordinate) => coordinate.Item2 >= 0 && coordinate.Item2 < Rows && coordinate.Item1 >= 0 && coordinate.Item1 < Cols; private bool CellAtCoordinateEquals(Cell cell, Tuple coordinate) => board[coordinate.Item2][coordinate.Item1] == cell; private HashSet> Adjacent(Cell cell, Tuple coordinate) { var row = coordinate.Item2; var col = coordinate.Item1; var coords = new[] { new Tuple(col + 1, row - 1), new Tuple(col, row - 1), new Tuple(col - 1, row ), new Tuple(col + 1, row ), new Tuple(col - 1, row + 1), new Tuple(col, row + 1) }; return new HashSet>(coords.Where(coord => IsValidCoordinate(coord) && CellAtCoordinateEquals(cell, coord))); } private bool ValidPath(Cell cell, Func, bool> stop, HashSet> processed, Tuple coordinate) { if (stop(board, coordinate)) return true; var next = Adjacent(cell, coordinate); next.ExceptWith(processed); if (!next.Any()) return false; return next.Any(nextCoord => { var updatedProcessed = new HashSet>(processed); updatedProcessed.Add(nextCoord); return ValidPath(cell, stop, updatedProcessed, nextCoord); }); } private bool IsWhiteStop(Cell[][] board, Tuple coordinate) => coordinate.Item2 == Rows - 1; private bool IsBlackStop(Cell[][] board, Tuple coordinate) => coordinate.Item1 == Cols - 1; private HashSet> WhiteStart() => new HashSet>(Enumerable.Range(0, Cols).Select(col => new Tuple(col, 0)).Where(coord => CellAtCoordinateEquals(Cell.White, coord))); private HashSet> BlackStart() => new HashSet>(Enumerable.Range(0, Rows).Select(row => new Tuple(0, row)).Where(coord => CellAtCoordinateEquals(Cell.Black, coord))); private bool ColorWins(Cell cell, Func, bool> stop, Func>> start) { return start().Any(coordinate => ValidPath(cell, stop, new HashSet>(), coordinate)); } private bool WhiteWins() => ColorWins(Cell.White, IsWhiteStop, WhiteStart); private bool BlackWins() => ColorWins(Cell.Black, IsBlackStop, BlackStart); public ConnectWinner Result() { if (WhiteWins()) return ConnectWinner.White; if (BlackWins()) return ConnectWinner.Black; return ConnectWinner.None; } }