Go Flood Fill Playground

GobanFloodFill.playground

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

enum Stone {
    case Black, White, None
    
    func opposite() -> Stone {
        switch self {
        case .Black:
            return .White
        case .White:
            return .Black
        default:
            return .Black
        }
    }
}

let gridSize = 9
var board: [[Stone]] = []

let row: [Stone] = Array(repeating: .None, count: gridSize)
board = Array(repeating: row, count: gridSize)

var views: [[UIView]] = []

let boardColor = UIColor(red: 0.75, green: 0.375, blue: 0.2, alpha: 1.0)

func drawGrid(view: UIView) {
    let widthOfCell = round(view.frame.width / CGFloat(gridSize))
    let heightOfCell = round(view.frame.height / CGFloat(gridSize))
    
    for (i, row) in board.enumerated() {
        var viewRow: [UIView] = []
        
        for (j, _) in row.enumerated() {
            let frame = CGRect(x: CGFloat(i)*widthOfCell, y: CGFloat(j)*heightOfCell, width: widthOfCell, height: heightOfCell)
            let cell = UIView(frame: frame)
            cell.backgroundColor = boardColor
            cell.layer.borderColor = UIColor.black.cgColor
            cell.layer.borderWidth = 2
            view.addSubview(cell)
            viewRow.append(cell)
        }
        views.append(viewRow)
    }
}

func createBoard() -> UIView {
    let frame = CGRect(x: 0, y: 0, width: 500, height: 500)
    let view = UIView(frame: frame)
    drawGrid(view: view)
    return view
}

var checked: [[Bool]] = []
var spots: [(Int,Int)] = []

//true = surrounded
func floodFill(x: Int, y: Int, stone: Stone) -> Bool {
    //stone is the color that is placed at the spot (x,y)

    //are we still in the grid?
    if x >= gridSize || x < 0 || y >= gridSize || y < 0 {
        return true
    }

    //have we already checked this spot
    if checked[x][y] {
        return true
    }
    checked[x][y] = true

    let spot = board[x][y]
    let target = stone.opposite()

    //is the spot that we're looking at the same color as what we're looking for? If so, we need to look in each direction
    if spot == stone {
        spots.append((x,y))
        
        //TODO: This could probably look a bit cleaner
        //south
        if floodFill(x: x, y: y+1, stone: stone) {
            //north
            if floodFill(x: x, y: y-1, stone: stone) {
                //west
                if floodFill(x: x-1, y: y, stone: stone) {
                    if floodFill(x: x+1, y: y, stone: stone) {
                        return true
                    }
                }
            }
        }

        return false
    } else if spot == target {
        return true
    } else {
        //empty spot
        return false
    }
}

//clear all of our checks. Use this before calling floodFill
func clearChecked() {
    let row = Array(repeating: false, count: gridSize)
    checked = Array(repeating: row, count: gridSize)
    spots = []
}

//adds a move to the board. It can also be used to remove a stone from the board
func addMove(x: Int, y: Int, stone: Stone) {
    let cell = views[x][y]
    board[x][y] = stone

    switch stone {
    case .None:
        cell.backgroundColor = boardColor
    case .White:
        cell.backgroundColor = UIColor.white
    case .Black:
        cell.backgroundColor = UIColor.black
    }

    if stone == .None {
        return
    }
    
    //Do we need to remove any stones?
    
    //TODO: neaten this up, so there's not so much copy paste
    //check group to the north
    if y > 0 && board[x][y-1] == stone.opposite() {
        clearChecked()
//        print("\(x), \(y)")
        if floodFill(x: x, y: y-1, stone: stone.opposite()) {
            print("Need to remove stone(s) to the north: \(spots)")
            for s in spots {
                addMove(x: s.0, y: s.1, stone: .None)
            }
        }
    }
    
    //south
    if y < gridSize-1 && board[x][y+1] == stone.opposite() {
        clearChecked()
        if floodFill(x: x, y: y+1, stone: stone.opposite()) {
            print("Need to remove stone(s) to the south: \(spots)")
            for s in spots {
                addMove(x: s.0, y: s.1, stone: .None)
            }
        }
    }
    
    //east
    if x < gridSize-1 && board[x+1][y] == stone.opposite() {
    clearChecked()
    if floodFill(x: x+1, y: y, stone: stone.opposite()) {
        print("Need to remove stone(s) to the east: \(spots)")
        for s in spots {
            addMove(x: s.0, y: s.1, stone: .None)
        }
    }
    }
    
    //west
    if x > 0 && board[x-1][y] == stone.opposite() {
        clearChecked()
        if floodFill(x: x-1, y: y, stone: stone.opposite()) {
            print("Need to remove stone(s) to the west: \(spots)")
            for s in spots {
                addMove(x: s.0, y: s.1, stone: .None)
            }
        }
    }
    
    //is this move legal?
    clearChecked()
    let illegal = floodFill(x: x, y: y, stone: stone)
    if illegal {
        print("Illegal Move: \(spots)")
        board[x][y] = .None
        cell.backgroundColor = boardColor
    }

}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = createBoard()


//standard ponnuki
func testPonuki() {
    addMove(x: 2, y: 3, stone: .Black)
    addMove(x: 3, y: 4, stone: .Black)
    addMove(x: 1, y: 4, stone: .Black)
    addMove(x: 2, y: 4, stone: .White)
    addMove(x: 2, y: 5, stone: .Black)
}


func testCorner() {
    addMove(x: 1, y: 0, stone: .Black)
    addMove(x: 0, y: 1, stone: .Black)
    addMove(x: 0, y: 0, stone: .White)
}


func testSide() {
    addMove(x: 3, y: 0, stone: .Black)
    addMove(x: 5, y: 0, stone: .Black)
    addMove(x: 4, y: 1, stone: .Black)
    addMove(x: 4, y: 0, stone: .White)
}


func testSurroundingTwo() {
    addMove(x: 2, y: 3, stone: .Black)
    addMove(x: 2, y: 6, stone: .Black)
    addMove(x: 1, y: 4, stone: .Black)
    addMove(x: 1, y: 5, stone: .Black)
    addMove(x: 3, y: 4, stone: .Black)
    addMove(x: 2, y: 4, stone: .White)
    addMove(x: 2, y: 5, stone: .White)
    addMove(x: 3, y: 5, stone: .Black)
}

func testSingleEye() {
    addMove(x: 2, y: 3, stone: .Black)
    addMove(x: 3, y: 3, stone: .Black)
    addMove(x: 4, y: 3, stone: .Black)
    addMove(x: 1, y: 4, stone: .Black)
    addMove(x: 1, y: 5, stone: .Black)
    addMove(x: 1, y: 6, stone: .Black)
    addMove(x: 5, y: 4, stone: .Black)
    addMove(x: 5, y: 5, stone: .Black)
    addMove(x: 5, y: 6, stone: .Black)
    addMove(x: 2, y: 7, stone: .Black)
    addMove(x: 3, y: 7, stone: .Black)
    addMove(x: 4, y: 7, stone: .Black)
    addMove(x: 3, y: 4, stone: .White)
    addMove(x: 4, y: 4, stone: .White)
    addMove(x: 4, y: 5, stone: .White)
    addMove(x: 2, y: 6, stone: .White)
    addMove(x: 3, y: 6, stone: .White)
    addMove(x: 4, y: 6, stone: .White)
    addMove(x: 2, y: 4, stone: .White)
    addMove(x: 2, y: 5, stone: .White)
    //removes last liberty, illegal move, should be true
    addMove(x: 3, y: 5, stone: .White)
    //removes white group, should be false
    addMove(x: 3, y: 5, stone: .Black)
}

func testDoubleEye() {
    addMove(x: 0, y: 7, stone: .White)
    addMove(x: 1, y: 7, stone: .White)
    addMove(x: 2, y: 7, stone: .White)
    addMove(x: 3, y: 7, stone: .White)
    addMove(x: 1, y: 8, stone: .White)
    addMove(x: 3, y: 8, stone: .White)
    
    addMove(x: 0, y: 6, stone: .Black)
    addMove(x: 1, y: 6, stone: .Black)
    addMove(x: 2, y: 6, stone: .Black)
    addMove(x: 3, y: 6, stone: .Black)
    addMove(x: 4, y: 7, stone: .Black)
    addMove(x: 4, y: 8, stone: .Black)
    //illegal move, double eye
    addMove(x: 0, y: 8, stone: .Black)
    //white takes the same spot, allowed
    addMove(x: 0, y: 8, stone: .White)
    //black now kills
    addMove(x: 2, y: 8, stone: .Black)
}

testDoubleEye()