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扁平数据结构转Tree ​

转森林 ​

  • 每一项 pid === 父节点 id；pid对应的父节点找不到，这一项为一棵新树的根节点

方法1 ​

js
const list = [
  { id: 1, name: '部门1', pid: 0 },
  { id: 2, name: '部门2', pid: 1 },
  { id: 3, name: '部门3', pid: 1 },
  { id: 4, name: '部门4', pid: 3 },
  { id: 5, name: '部门5', pid: 4 },
  { id: 6, name: '部门1', pid: null },
  { id: 7, name: '部门2', pid: 6 },
]

function buildForest(list) {
  const result = []
  const map = new Map()

  // Map()  id : node
  for (const item of list)
    map.set(item.id, { ...item, children: [] })

  for (const node of list) {
    const parent = map.get(node.pid)
    if (parent)
      parent.children.push(map.get(node.id))
    else
      result.push(map.get(node.id))

  }
  return result
}
const list = [
  { id: 1, name: '部门1', pid: 0 },
  { id: 2, name: '部门2', pid: 1 },
  { id: 3, name: '部门3', pid: 1 },
  { id: 4, name: '部门4', pid: 3 },
  { id: 5, name: '部门5', pid: 4 },
  { id: 6, name: '部门1', pid: null },
  { id: 7, name: '部门2', pid: 6 },
]

function buildForest(list) {
  const result = []
  const map = new Map()

  // Map()  id : node
  for (const item of list)
    map.set(item.id, { ...item, children: [] })

  for (const node of list) {
    const parent = map.get(node.pid)
    if (parent)
      parent.children.push(map.get(node.id))
    else
      result.push(map.get(node.id))

  }
  return result
}

方法2 ​

递归 判断是否为根节点，是根节点构造树

js
function buildForest(data) {
  const nodeMap = new Map()

  // 构建节点映射
  for (const item of data)
    nodeMap.set(item.id, { ...item, children: [] })

  function buildTree(id) {
    const node = nodeMap.get(id)
    for (const item of data) {
      if (item.pid === id) {
        const child = buildTree(item.id)
        if (child)
          node.children.push(child)

      }
    }
    return node
  }

  const forest = []
  for (const item of data) {
    const parent = nodeMap.get(item.pid)
    if (!parent) {
      const tree = buildTree(item.id)
      if (tree)
        forest.push(tree)

    }
  }

  return forest
}
function buildForest(data) {
  const nodeMap = new Map()

  // 构建节点映射
  for (const item of data)
    nodeMap.set(item.id, { ...item, children: [] })

  function buildTree(id) {
    const node = nodeMap.get(id)
    for (const item of data) {
      if (item.pid === id) {
        const child = buildTree(item.id)
        if (child)
          node.children.push(child)

      }
    }
    return node
  }

  const forest = []
  for (const item of data) {
    const parent = nodeMap.get(item.pid)
    if (!parent) {
      const tree = buildTree(item.id)
      if (tree)
        forest.push(tree)

    }
  }

  return forest
}