Apple Swift - Generate combinations with repetition

Question

I\'m trying to generate a nested array containing all combinations with repetition in Apple\'s Swift programming language.

An detailed explanation of combinations wi

Answer 1

The main mistake I was making was to use a var named the same as my function:

combos += combos(array, k)

Which is why I was seeing an error on this line and the other line where my function was being called.

After fixing that the rest of the problems were easier to solve :)

In case it will help anyone here's my working function:

func combos(var array: Array, k: Int) -> Array> {
    if k == 0 {
        return [[]]
    }

    if array.isEmpty {
        return []
    }

    let head = array[0]

    var ret: Array> = []
    var subcombos = combos(array, k - 1)
    for subcombo in subcombos {
        var sub = subcombo
        sub.insert(head, atIndex: 0)
        ret.append(sub)
    }
    array.removeAtIndex(0)
    ret += combos(array, k)

    return ret
}

If anyone can improve it I'd be happy

For example can anyone explain how to get rid of the line var sub = subcombo. i.e. how do I make subcombo mutable by default?