DSA Hashmap vs Treemap

Feature	HashMap	TreeMap
Implementation	Uses a hash table internally.	Uses a red-black tree internally.
Ordering	No specific order, elements are stored randomly.	Sorted order (natural or custom comparator).
Duplicates	Allows only one null key and multiple null values.	Allows only one null key (null values are allowed).
Performance	Faster for most operations (`O(1)` average for `get()`, `put()`, `remove()`).	Slower (`O(log n)`) for `get()`, `put()`, `remove()` due to tree traversal.
Use Case	When order of elements is not important, and you need fast access.	When you need elements to be sorted (ascending or custom order).
Iteration Order	No guaranteed order during iteration.	Iterates in sorted order.
Memory Usage	Less memory overhead due to hash table.	More memory due to the tree structure.
Methods	Doesn’t provide methods for range queries.	Provides methods like `subMap()`, `headMap()`, `tailMap()` for range queries.

HashMap:
- No order guaranteed.
- Faster (O(1) average for get(), put(), remove()).
- Allows one null key and multiple null values.
TreeMap:
- Always sorted (ascending or custom order).
- Slower (O(log n) for get(), put(), remove()).
- Allows one null key but only non-null values.

Use HashMap when you don’t care about the order of elements, and you want fast access to values by keys.
Use TreeMap when you need elements sorted in ascending order (or custom order using a comparator), and you are okay with slightly slower performance.

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