Validates a sudoku puzzle.

SudokuValidator.swift

import Foundation

func validateSudoku(array : [Int]) -> Bool {
    let width = 9
   
    func valueAtPos(x: Int, y: Int, array: [Int]) -> Int {
        return array[y * width + x]
    }
    
    func validateGroup(array:[Int]) -> Bool {
        var allThereSet = Set<Int>()
        array.map { allThereSet.insert($0) }
        return allThereSet.count == 9
    }

    for y in 0..<9 {
        if !validateGroup(array: (0..<9).map { valueAtPos(x: $0, y: y, array: array)}) {
            return false
        }
    }
    
    for x in 0..<9 {
        if !validateGroup(array: (0..<9).map { valueAtPos(x: x, y: $0, array: array)}) {
            return false
        }
    }
    
    for y in 0..<3 {
        let first =  (0..<3).map { valueAtPos(x: $0 * 1, y: y * 1, array: array)}
        let second = (0..<3).map { valueAtPos(x: $0 * 2, y: y * 2, array: array)}
        let third =  (0..<3).map { valueAtPos(x: $0 * 3, y: y * 3, array: array)}
        if validateGroup(array: first + second + third) {
            return false
        }
    }
    
    return true
}

assert(!validateSudoku(array:Array(
    [[1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9],
     [1,2,3,4,5,6,7,8,9]].joined())))

assert(validateSudoku(array:Array(
    [[5,1,3,6,8,7,2,4,9],
     [8,4,9,5,2,1,6,3,7],
     [2,6,7,3,4,9,5,8,1],
     [1,5,8,4,6,3,9,7,2],
     [9,7,4,2,1,8,3,6,5],
     [3,2,6,7,9,5,4,1,8],
     [7,8,2,9,3,4,1,5,6],
     [6,3,5,1,7,2,8,9,4],
     [4,9,1,8,5,6,7,2,3]].joined())))

assert(!validateSudoku(array:Array(
    [[5,1,3,6,8,7,2,4,9],
     [8,4,9,5,2,1,6,3,7],
     [2,6,7,3,4,8,5,9,1],
     [1,5,8,4,6,3,9,7,2],
     [9,7,4,2,1,8,3,6,5],
     [3,2,6,7,9,5,4,1,8],
     [7,8,2,9,3,4,1,5,6],
     [6,3,5,1,7,2,8,9,4],
     [4,9,1,8,5,6,7,2,3]].joined())))