ListNode with description

ListNode.swift

public class ListNode: ExpressibleByArrayLiteral {
    public var value: Int
    public var next: ListNode?
    public init(_ value: Int, next: ListNode? = nil) {
        self.value = value
        self.next = next
    }
    
    public required init(arrayLiteral elements: Int...) {
        self.value = elements[0]
        var current = self
        
        for element in elements.dropFirst() {
            let next = ListNode(element)
            current.next = next
            current = next
        }
    }
}

extension ListNode: CustomStringConvertible {
    public var description: String {
        let description = "\(value) -> "
        if let next = next {
            return description + next.description
        } else {
            return description + "nil"
        }
    }
}