Snakes and Ladders

snakes-and-ladders.swift

class Solution {
    var moves = 0
    var rows = 0
    var cols = 0
    func snakesAndLadders(_ board: [[Int]]) -> Int {
        let newBoard = convertTo1D(board)
        print(newBoard)
        let n = board.count
        var queue: [Int] = []
        var visited: [Bool] = Array(repeating: false, count: n * n)
        queue.append(0)
        visited[0] = true

        while !queue.isEmpty {
            var size = queue.count
            while size > 0 {
                let square = queue.removeFirst()
                if square == n * n - 1 { return moves }

                for var next in square + 1..<min(square + 6, n * n - 1) {
                    let square2 = newBoard[next]
                    if square2 > 0 { next = square2 - 1 }
                    if !visited[next] { 
                        visited[next] = true
                        queue.append(next) 
                    }
                }
                size -= 1
            }
            print(queue)
            moves += 1
        }
        return -1
    }

    private func convertTo1D(_ board: [[Int]]) -> [Int] {
        let n = board.count
        var newBoard: [Int] = []
        for row in (0..<n).reversed() {
            for col in 0..<n {
                if row % 2 == n % 2 {
                    newBoard.append(board[row][n - col - 1])
                } else {
                    newBoard.append(board[row][col])
                }
            }
        }
        return newBoard
    }
}

let input = [[-1,-1,-1,-1,-1,-1],[-1,-1,-1,-1,-1,-1],[-1,-1,-1,-1,-1,-1],[-1,35,-1,-1,13,-1],[-1,-1,-1,-1,-1,-1],[-1,15,-1,-1,-1,-1]]
print(Solution().snakesAndLadders(input))