Ordered v Unordered Associative Containers

• Ordered Associative Container
• Standard Traversal encounters elements in sorted order
• Order predicate may be specified
• Default order predicate is "less than", defined using operator< for the element type
• Popular implementations: OrderedVector, BinarySearchTree
• Search operations required to have O(log n) runtime
• Insert, Remove operations should either be seldom used or have O(log n) runtime
• Unordered Associative Container
• Standard Traversal encounters elements in unspecified order
• Search, Insert, Remove operations should have average-case constant runtime
• Popular implementations use hashing