Summary of Map Types:

Map Type                 Unique Keys	Key Order	        Internal Structure	Time Complexity (average)
std::map	                 Yes	    Sorted (ascending)	 Binary Search Tree	    O(log n)
std::multimap	             No	        Sorted (ascending)	 Binary Search Tree	    O(log n)
std::unordered_map	         Yes	    Unordered	         Hash Table	             O(1)
std::unordered_multimap	      No	    Unordered	         Hash Table	             O(1)


Choosing the Right Map:
Use std::map when you need sorted and unique keys.
Use std::multimap when you need sorted but non-unique keys.
Use std::unordered_map when you need fast access and unique keys, but don’t care about the order.
Use std::unordered_multimap when you need fast access with non-unique keys, and don’t care about the order.