Node.js

export class Node {
  constructor(val, neighbors) {
    this.val = val === undefined ? 0 : val
    this.neighbors = neighbors === undefined ? [] : neighbors
  }

  static parse(edges) {
    const nodeMap = new Map()

    // 创建节点
    const getNode = (val) => {
      if (!nodeMap.has(val)) {
        const newNode = new Node(val)
        nodeMap.set(val, newNode)
      }
      return nodeMap.get(val)
    }

    // 连接节点
    edges.forEach((neighbors, index) => {
      const val = index + 1
      const currentNode = getNode(val)
      neighbors.forEach((neighborVal) => {
        const neighborNode = getNode(neighborVal)
        currentNode.neighbors.push(neighborNode)
      })
    })

    return nodeMap.size > 0 ? nodeMap.values().next().value : null
  }

  static toArray(node) {
    if (!node)
      return []

    const visited = new Set()
    const result = []

    const dfs = (currentNode) => {
      if (visited.has(currentNode.val))
        return

      const { neighbors, val } = currentNode
      visited.add(val)
      result.push(neighbors.map(({ val }) => val))
      currentNode.neighbors.forEach((neighbor) => {
        dfs(neighbor)
      })
    }

    dfs(node)

    return result
  }
}