What is the performance of std::unordered_set in C++11?

What is the performance of std::unordered_set in C++11?

The performance of std::unordered_set in C++11 is generally O(1) for insertions, deletions, and lookups on average.

Are there any worst-case scenarios I should be aware of?

Yes, in the worst case, performance can degrade to O(n) if many elements hash to the same bucket, causing collisions.

How does it compare to std::set?

std::set is implemented as a balanced tree, providing O(log n) performance for insertions and lookups, which can be slower than std::unordered_set.

When should I use std::unordered_set over std::set?

Use std::unordered_set when you need faster average performance for lookups and don't require ordered elements.