Build Tree From Comment History | Dataford Interview Questions

Given a parent-child comment history, how would you create a tree?

Implement build_comment_tree(history). Each history item is a dictionary with parent_id and comment_id; parent_id is null for a root comment. Return a list of root nodes, where each node has the shape {"id": comment_id, "children": [...]}. Preserve the order in which roots and children first appear. Assume every comment has at most one parent and the relationships form a forest.

Constraints

0 <= len(history) <= 10^4
Each history item contains exactly one parent_id and one comment_id
comment_id values are non-null and unique as comment identifiers
Each comment has at most one parent
Relationships form an acyclic forest
Parent and comment IDs are strings

Function Signature

def build_comment_tree(history):

Your question is Build Tree From Comment History. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Given a parent-child comment history, how would you create a tree?

Constraints

0 <= len(history) <= 10^4
Each history item contains exactly one parent_id and one comment_id
comment_id values are non-null and unique as comment identifiers
Each comment has at most one parent
Relationships form an acyclic forest
Parent and comment IDs are strings

Function Signature

def build_comment_tree(history):

Your question is Build Tree From Comment History. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.