maximum line in matrix - Nov. 25, 2020

maximumLineInMatrix.cs

 public int LongestLine(int[][] M) {
        if(M == null || M.Length == 0 || M[0].Length == 0)
        {
            return 0; 
        }
        
        var rows = M.Length; 
        var columns = M[0].Length; 
        
        var dpH = new int[rows][];
        var dpV = new int[rows][];
        var dpD = new int[rows][];
        
        for(var row = 0; row < rows; row++)
        {
            dpH[row] = new int[columns];
            dpV[row] = new int[columns];
            dpD[row] = new int[columns];
        }
        
        var max = 0; 
        for(int row = 0; row < rows; row++)
        {
            for(int col = 0; col < columns; col++)
            {
                var current = M[row][col];
                var isOne = current == 1; 
                if(isOne)
                {
                    dpH[row][col] = 1 + (col > 0?  dpH[row][col - 1] : 0);
                    dpV[row][col] = 1 + (row > 0?  dpV[row - 1][col] : 0);
                    dpD[row][col] = 1 + ((col > 0 &&  row > 0)? dpD[row - 1][col - 1] : 0);
                    
                    var array = new int[]{ dpH[row][col],  dpV[row][col],  dpD[row][col]};
                    
                    max = Math.Max(max, array.Max());
                }
            }
        }
        
        return max; 
    }