Hanoi Tower

calculate_hanoi.swift

/*
 Hanoi Tower
 Calucuating How many moves in Swift
 result is 2^n - 1
 */
func hanoi(_ n: Int, from: String="from", target: String="target", other: String="other") -> Int {
    guard n != 0 else { return 0 }
    // move top of n-1 disks on from to other
    var count = hanoi(n-1, from: from, target: other, other: target)

    // move the last disk to target
    count += 1

    // move n-1 disks on other to target
    count += hanoi(n-1, from: other, target: target, other: from)

    return count
}

print(hanoi(3)) // 7
print(hanoi(4)) // 15
print(hanoi(5)) // 31