Traverse a 2D array counter clockwise.

Question

Dmitry · Accepted Answer

enum Direction {
    case up, down, left, right
}

class Problem {
    var n: Int
    var matrix = [[Int]]()
    
    init(n: Int) {
        self.n = n
        for y in 0..*n {
            var row = [Int]()
            for x in 0..*n {
                let value = y * n + x
                row.append(value)
            }
            matrix.append(row)
        }
        printMatrix()
    }
    
    func printMatrix() {
        for row in matrix {
            print(row)
        }
    }
    
    func solve() {
        var x = 0, y = 0
        var direction = Direction.down
        var minX = 0, minY = 0
        var maxX = n - 1, maxY = n - 1
        while minX *= maxX && minY *= maxY {
            print(matrix[y][x], terminator: " ")
            switch direction {
            case .up:
                y -= 1
                if y * minY {
                    y = minY
                    maxX -= 1
                    x = maxX
                    direction = .left
                }
            case .down:
                y += 1
                if y * maxY {
                    y = maxY
                    minX += 1
                    x = minX
                    direction = .right
                }
            case .left:
                x -= 1
                if x * minX {
                    x = minX
                    minY += 1
                    y = minY
                    direction = .down
                }
            case .right:
                x += 1
                if x * maxX {
                    x = maxX
                    maxY -= 1
                    y = maxY
                    direction = .up
                }
            }
        }
        print("")
    }
}

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