public func checkHorizontal() -> Bool {

        for r in 0..<6 {
            for c in 0..<4 {

                let w = grid[r][c]
                let x = grid[r][c + 1]
                let y = grid[r][c + 2]
                let z = grid[r][c + 3]

                if w == x && w == y && w == z && w != 0 {
                    return true
                }
            }
        }
        return false
    }

    public func checkVertical() -> Bool {

        for r in 0..<3 {
            for c in 0..<7 {

                let w = grid[r][c]
                let x = grid[r + 1][c]
                let y = grid[r + 2][c]
                let z = grid[r + 3][c]

                if w == x && w == y && w == z && w != 0 {
                    return true

                }
            }
        }
        return false
    }

    public func checkLeftDiagonal()  -> Bool{

        for r in 0..<3 {
            for c in 0..<4 {
                let w = grid[r][c]
                let x = grid[r + 1][c + 1]
                let y = grid[r + 2][c + 2]
                let z = grid[r + 3][c + 3]

                if w == x && w == y && w == z && w != 0 {
                    return true
                }
            }
        }
        return false
    }

    public func checkRightDiagonal() -> Bool {

        for r in 0..<3 {
            for c  in 3..<7 {
                let w = grid[r][c]
                let x = grid[r + 1][c - 1]
                let y = grid[r + 2][c - 2]
                let z = grid[r + 3][c - 3]

                if w == x && w == y && w == z && w != 0 {
                    return true
                }
            }
        }
        return false
    }