[5Kyu] Linked Lists - Front Back Split(정리중)

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1. Swift

1-1. My Solution

enum LinkedError : Error {
  case nilError
  case lessLength
}
class Node {
    var data: Int
    var next: Node?
    init(_ data: Int) {
        self.data = data
    }
}

func frontBackSplit(source: Node?, front: inout Node?, back: inout Node?) throws {
  guard let _source = source else {
    throw LinkedError.nilError
  }
  var isNilBreak = false
  var currentNode : Node? = _source
  var nodeIntValue : [Int] = []
  while !isNilBreak {
    nodeIntValue.append(currentNode!.data)
    if currentNode?.next == nil {
      isNilBreak = true
    }else{
      currentNode = currentNode?.next
    }
  }
  guard !(nodeIntValue.count < 2) else {
    throw LinkedError.lessLength
  }
  let frontLength = Int(ceil(Double(nodeIntValue.count) / 2))
  let testNodeArr = buildListFromArray([1, 2])
  var firstNodeTemp : Node?
  var secondNodeTemp: Node?
  for i in 0 ..< frontLength {
    nodeInsert(node: &firstNodeTemp, data: nodeIntValue[i])
  }
  for i in frontLength ..< nodeIntValue.count {
    nodeInsert(node: &secondNodeTemp, data: nodeIntValue[i])
  }
  front = firstNodeTemp
  back = secondNodeTemp
}
private func nodeInsert(node : inout Node?, data : Int) {
  guard node != nil else {
    node = .init(data)
    return
  }
  if let _ = node?.next {
    nodeInsert(node: &node!.next, data: data)
  }else{
    node?.next = .init(data)
  }
}

1-2. Best Solution

extension Int : Error {}

class Node {
    var data: Int
    var next: Node?
    init(_ data: Int) {
        self.data = data
    }
}

func frontBackSplit(source: Node?, front: inout Node?, back: inout Node?) throws {

    guard source?.next != nil else {throw 1}
    
    front = source
    back = source
    
    while back!.next?.next != nil
    {
        front = front!.next
        back = back!.next!.next
    }

    back = front!.next
    front!.next = nil
    front = source
    
    return
}