Simple implementation of hanoi algorithm. If you want more information about this algorithm watch this video https://www.youtube.com/watch?v=3YH0SZYAzOQ

hanoi.swift

enum Tower:String {
    case A
    case B
    case C
}

func hanoi(_ disk: Int, from: Tower, using: Tower, 
           to: Tower, output: inout [String]) {
    if disk == 1 {
        output.append("\(from.rawValue)->\(to.rawValue)")
        return
    }
    hanoi(disk - 1, from: from, using: to, to: using,
          output: &output)
    hanoi(1, from: from, using: using, to: to,
          output: &output)
    hanoi(disk - 1, from: using, using: from, to: to, 
          output: &output)
}

var result:[String] = []

hanoi(3, from: .A, using: .B, to: .C, output: &result)

let out = result.joined(separator:", ")
print(out)
//A->C, A->B, C->B, A->C, B->A, B->C, A->C