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'},
]

其结果：

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，但在我的情况下，我需要使用next_id顺序可视化数组中的数据。

PS即使知道本机解决方案也很好，然后我可以尝试自己转换为Ramda.js

Answer 1

原生方法

您可以按id排序并选择最低的id作为所需输出的第一个元素，然后您可以通过使用属性next_id查找下一个节点来推送下一个元素。

 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'}], result = [[...dll].sort((a, b) => a.id - b.id).shift()]; dll.forEach(() => result.push(dll.find(({id}) => id === result[result.length - 1].next_id))); console.log(result);

Answer 2

通过id创建项目的 am 索引，找到第一个项目（ prev_id === null ），然后用 while 循环迭代，并将当前对象推入结果数组：

 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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