Explain Union-Find for dynamic connectivity problems
Reported in SumUp European engineering loops. Disjoint set union structure used in graph connectivity interviews.
Interview scenario
Context for SumUp candidates:
Support union(a,b) and connected(a,b) operations over changing groups.
Model answer
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Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at SumUp: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
Union-Find keeps each node pointing to a parent representative. find(x) returns root parent, and union(a,b) merges roots when they differ.
With path compression and union by rank/size, operations become near constant amortized time. This is ideal for problems like cycle detection in undirected graphs and Kruskal minimum spanning tree.
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