Algorithm interview from Google

Question

I am a long time lurker, and just had an interview with Google where they asked me this question:

Various artists want to perform at the Royal Albert Hall and you are re

Answer 1

Why not try to use Union-Find? You can group each concert day + the next 5 days as part of one set and then perform a FIND on the given day which would return the next set ID which would be your next concert date.

If implemented using a tree, this gives a O(log n) time complexity.