Graph Theory37 sections · 1633 units
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Lessons Learned

(What you practiced)

You practiced building the upup table from a parent array. You implemented the binary decomposition loop to answer queries. You also handled edge cases: queries where kk exceeds depth.

This problem is the template for all binary lifting problems. If you can solve this, you can solve any kk-th ancestor problem. The same table structure is reused for LCA queries, path aggregation, and other tree problems that need fast ancestor lookups.