通过下一个ID Ramda.js对双向链接列表进行排序 [英] Sort doubly linked list by next id Ramda.js
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问题描述
我想按 next_id
值对双向链表进行排序.
I want to sort doubly linked list by next_id
value.
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
顺序显示数组中的数据.
I understand that it may not make sense to sort the DLL, but in my case I need to sequentially visualize the data from the array using next_id
.
P.S.很高兴知道一个本机解决方案,然后我可以尝试自己转换为Ramda.js
P.S. It would be nice to know even a native solution, and then I could try to convert to Ramda.js myself
推荐答案
通过 id
创建项目索引,找到第一个项目( prev_id
=== null),然后使用while循环进行迭代,然后将当前对象推入结果数组:
Create am index of items by id
, find the 1st item (prev_id
=== null), and then iterate with a while loop, and push the current object into the result array:
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)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script>
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