stringFunc

//print all permutuations of a string
//for example ab -> ab ba suppose all the letters are uniqe
// 1. if it's only one letter print it and exit


func permutations(n:Int, inout _ a:Array<Character>) {
    if n == 1 {print(a); return}
    for i in 0..<n-1 {
        permutations(n-1,&a)
        swap(&a[n-1], &a[(n%2 == 1) ? 0 : i])
    }
    permutations(n-1,&a)
}

var arr = Array("ABC".characters)
permutations(arr.count,&arr)
print("//////////////")
func permutations1(n:Int,var a:Array<Character>) {
    if n == 1 {print(a); return}
    for i in 0..<n-1 {
        permutations1(n-1,a: a)
        print(n%2)
        ////////0)
        a[n-1] = a[(n%2 == 1) ? 0 : i]
    }
    permutations1(n-1,a: a)
}

var arr1 = Array("ABC".characters)
permutations1(arr1.count,a: arr1)

//reverse string
func reverseStr(s:String)->String
{
    var tempArr:Array<Character> = Array(s.characters)
    var i = s.characters.count-1
        for c in s.characters
        {
        tempArr.removeAtIndex(i)
        tempArr.insert(c, atIndex: i)
        i -= 1
    }
    return String(tempArr)
}
reverseStr("Hello")