javascript - 按下一个 id 对双向链表进行排序 Ramda.js

Question

我想按 next_id 值对双向链表进行排序。

我的DLL:

const dll = [
  {id: '22', prev_id: '41', next_id: '45'},
  {id: '45', prev_id: '22', next_id: null},
  {id: '41', prev_id: '14', next_id: '22'},
  {id: '14', prev_id: null, next_id: '41'},
]

结果:

const dll_result = [
  {id: '14', prev_id: null, next_id: '41'}, // next item - 41
  {id: '41', prev_id: '14', next_id: '22'}, // next item - 22
  {id: '22', prev_id: '41', next_id: '45'}, // next item - 45
  {id: '45', prev_id: '22', next_id: null},
]

我知道对 DLL 进行排序可能没有意义，但就我而言，我需要使用 next_id 按顺序可视化数组中的数据。

P.S. 如果知道一个原生解决方案就好了，然后我可以尝试自己转换为 Ramda.js

Answer 1

通过id创建项目索引，找到第一个项目(prev_id === null)，然后用while循环进行迭代，并推送当前对象进入结果数组:

const findStart = R.find(R.propEq('prev_id', null))
const indexById = R.indexBy(R.prop('id'))

const sortByNextId = arr => {
  const index = indexById(arr)
  let current = findStart(arr)
  
  const sorted = []
  
  while(current) {
    sorted.push(current)
    current = index[current.next_id]
  }
  
  return sorted
}

const dll = [
  {id: '22', prev_id: '41', next_id: '45'},
  {id: '45', prev_id: '22', next_id: null},
  {id: '41', prev_id: '14', next_id: '22'},
  {id: '14', prev_id: null, next_id: '41'},
]

const result = sortByNextId(dll)

console.log(result)

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