What are the performance differences between map and unordered_map in C++11?

What are the performance differences between map and unordered_map in C++11?

In C++11, map is implemented as a balanced binary tree, while unordered_map uses a hash table. This leads to different performance characteristics.

Can you explain the time complexity for both?

Sure! map has a time complexity of O(log n) for insertions, deletions, and lookups. In contrast, unordered_map has an average time complexity of O(1) for these operations, but O(n) in the worst case.

When should I use one over the other?

Use map when you need ordered elements or range queries. Use unordered_map for faster access when order doesn't matter.

Are there any memory usage differences?

Yes, unordered_map typically uses more memory due to its hash table structure, which requires additional space for buckets.