On Mon, 11 Dec 2023 01:28:29 GMT, Valeh Hajiyev <d...@openjdk.org> wrote:
> This commit addresses the current limitation in the `PriorityQueue` > implementation, which lacks a constructor to efficiently create a priority > queue with a custom comparator and an existing collection. In order to create > such a queue, we currently need to initialize a new queue with custom > comparator, and after that populate the queue using `addAll()` method, which > in the background calls `add()` method (which takes `O(logn)` time) for each > element of the collection (`n` times). This is resulting in an overall time > complexity of `O(nlogn)`. > > > PriorityQueue<String> pq = new PriorityQueue<>(customComparator); > pq.addAll(existingCollection); > > > The pull request introduces a new constructor to streamline this process and > reduce the time complexity to `O(n)`. If you create the queue above using > the new constructor, the contents of the collection will be copied (which > takes `O(n)` time) and then later `heapify()` operation (Floyd's algorithm) > will be called once (another `O(n)` time). Overall the operation will be > reduced from `O(nlogn)` to `O(2n)` -> `O(n)` time. > > > PriorityQueue<String> pq = new PriorityQueue<>(existingCollection, > customComparator); This pull request has been closed without being integrated. ------------- PR: https://git.openjdk.org/jdk/pull/17045
