**Contents**show

## What is difference between Hashmap and TreeSet?

Hash set and tree set both belong to the collection framework. HashSet is the implementation of the Set interface whereas Tree set implements sorted set. Tree set is backed by TreeMap while HashSet is backed by a hashmap. … **The tree set does not allow the null object**.

## What is difference between PriorityQueue and Set?

Differences between PriorityQueue and TreeSet

TreeSet uses the Set underlying data structure. In PriorityQueue, apart from the root **rest of the elements may or may not follow any order**. In TreeSet all the elements remain in the sorted order. Using PriorityQueue, we can retrieve largest or smallest element in O(1) time.

## What is difference between TreeSet and TreeMap in Java?

1. Major difference between TreeSet and TreeMap is that **TreeSet implements Set interface while TreeMap implements Map interface in Java**. … TreeSet stores only one object while TreeMap uses two objects called key and Value. Objects in TreeSet are sorted while keys in TreeMap remain in sorted order.

## What is difference between TreeSet and HashSet in Java?

**HashSet is faster than TreeSet**. HashSet is Implemented using a hash table. TreeSet takes O(Log n) for search, insert and delete which is higher than HashSet. But TreeSet keeps sorted data.

## Why do we use TreeSet?

TreeSet is one of the most important implementations of the SortedSet interface in Java that uses **a Tree for storage**. The ordering of the elements is maintained by a set using their natural ordering whether or not an explicit comparator is provided.

## Which is faster TreeMap or HashMap?

HashMap is a general purpose Map implementation. It provides a performance of O(1) , while TreeMap provides a performance of O(log(n)) to add, search, and remove items. Hence, **HashMap is usually faster**.

## Is a priority queue a heap?

A priority queue **acts like a queue in that you dequeue** an item by removing it from the front. However, in a priority queue the logical order of items inside a queue is determined by their priority. … The classic way to implement a priority queue is using a data structure called a binary heap.

## What are priority queues used for?

The priority queue (also known as the fringe) is used **to keep track of unexplored routes**, the one for which a lower bound on the total path length is smallest is given highest priority. Heap Sort : Heap sort is typically implemented using Heap which is an implementation of Priority Queue.

## Is set a priority queue?

Every element of std::set is stored at its own allocation. std::priority_queue (with underlying std::vector container by default) uses single allocation to store all elements. On other hand std::priority_queue uses many swap operations on its elements whereas std::set uses just pointers swapping.

## What is SortedSet in Java?

SortedSet , is **a subtype of the java.** **util.** **Set interface**. The Java SortedSet interface behaves like a normal Set with the exception that the elements it contains are sorted internally. This means that when you iterate the elements of a SortedSet the elements are iterated in the sorted order.

## What is TreeSet and TreeMap?

Implementation : **TreeMap is a red-black tree based NavigableMap implementation**. TreeSet is a NavigableSet implementation based on a TreeMap. Sorting : TreeMap is sorted based on keys while TreeSet is sorted based on objects.