import UIKit
import Foundation

var digits = 3...1000

var arr = Array([Int](digits.lowerBound..<digits.upperBound))

var divisibles = Array<Int>()

var permutablesArr = Array<Array<Character>>()


for idx in arr {
    if(idx % 8 == 0) {
        if (idx % 10 == 0) {
            divisibles.append(idx)
        }
    }
}

func arrCh(a: Array<Character>) -> Array<Character> {
    let arrC:Array<Character> = a
    let newStr = arrC.map({$0})
    return newStr
}

//MARK: print our permutations as an array...
func newPermute(n:Int, _ a: inout Array<Character>) -> Array<Character> {
    if n == 1 {print(a); return ["ryan".characters.first!]}
    for i in 0..<n-1 {
        newPermute(n: n-1, &a)
        swap(&a[n-1], &a[(n%2 == 1) ? 0 : i ])
        let newString = arrCh(a:a)
        permutablesArr.append(newString)
    }

    return a
}

//MARK: loop over all our divisible by 8 obvious numbers, and convert from array to int then push into new obj...

divisibles.flatMap{$0}.forEach { (anyNum : Int) -> () in
    let numToStr = String(anyNum)
    var strArr = Array(numToStr.characters)
    let c = arrCh(a: strArr)
    permutablesArr.append(c)
    var backInArr = Array<String>()
    for j in c {
        if let elm = j as Character? {
            let strs = String(elm)
            backInArr.append(strs)
        }
    }
    let list = backInArr.joined(separator: "")
    let lastPermutation = newPermute(n: strArr.count, &strArr)

}

var allPermutablesDivisibleBy8 = Array<Int>()

for item in permutablesArr {
    if let itm = item as Array<Character>? {
        let st = String(itm)
        let asInt = (st as NSString).integerValue
        if(asInt % 8 == 0) {
            allPermutablesDivisibleBy8.append(asInt)
        }

    }
}

print("//////////////////////All numbers from permutation & 3...1000 that are divisible by 8")
allPermutablesDivisibleBy8 = Array(Set(allPermutablesDivisibleBy8))

print("divisible by \(allPermutablesDivisibleBy8.sorted())") // put back into incremental order...