How should I practice Recursive Display Sort?

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Problem · Array

Recursive Display Sort

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● Hard

FigmaFULLTIMEPHONE SCREENONSITE INTERVIEW

Problem statement

You are given n display nodes through parallel arrays. Node i has identifier ids[i], parent index parents[i], horizontal coordinate x[i], and inclusive vertical interval [top[i], bottom[i]]. A parent index of -1 marks a root.

Sort each sibling list independently:

Place siblings in the same group when their vertical intervals overlap directly or transitively.
Order groups from top to bottom by their minimum top coordinate.
Within a group, order nodes by increasing x, then increasing top, then original input index.

Return all identifiers in preorder: emit each sorted node, then recursively emit its sorted children. Apply the same sibling rule to the roots and to every child list.

Function

sortDisplayNodes(ids: String[], parents: int[], x: int[], top: int[], bottom: int[]) → String[]

Examples

Example 1

ids = ["A","B","C"]parents = [-1,-1,-1]x = [30,10,20]top = [0,5,30]bottom = [10,15,40]return = ["B","A","C"]

A and B overlap, so their group uses horizontal order B, A. The disjoint group containing C comes below it.

Example 2

ids = ["rootB","rootA","childR","childL"]parents = [-1,-1,1,1]x = [20,5,30,10]top = [0,0,10,12]bottom = [5,5,20,18]return = ["rootA","childL","childR","rootB"]

The roots overlap and sort by x. Preorder emits rootA, its horizontally sorted children, and then rootB.

Example 3

ids = ["A","B","C"]parents = [-1,-1,-1]x = [30,10,20]top = [0,3,7]bottom = [4,8,10]return = ["B","C","A"]

A overlaps B, and B overlaps C, so all three belong to one transitive group and sort by x.

Constraints

1 <= n <= 100000, and all five arrays have length n.
Identifiers are unique non-empty strings of at most 50 characters.
Each parent is -1 or a valid node index, and the parent links form a forest.
-10^9 <= x[i], top[i], bottom[i] <= 10^9.
top[i] <= bottom[i].
Intervals that share an endpoint overlap.