https://github.com/chucnorrisful/vEB

Go implementation of the van Emde Boas tree data structure: Priority queue for positive whole numbers in O(log log u) time.
https://github.com/chucnorrisful/vEB

go golang priority-queue van-emde-boas van-emde-boas-tree

Last synced: 2 months ago
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Go implementation of the van Emde Boas tree data structure: Priority queue for positive whole numbers in O(log log u) time.

• Host: GitHub
• URL: https://github.com/chucnorrisful/vEB
• Owner: chucnorrisful
• Created: 2021-09-07T14:06:40.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2023-11-05T13:44:11.000Z (about 1 year ago)
• Last Synced: 2024-08-03T23:19:16.281Z (6 months ago)
• Topics: go, golang, priority-queue, van-emde-boas, van-emde-boas-tree
• Language: Go
• Homepage:
• Size: 43 KB
• Stars: 4
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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• awesome-golang-repositories - vEB

README

        
# vEB

Go implementation of the van Emde Boas tree data structure: Priority queue for positive whole numbers in O(log log u) time.

## Supports the following Priority-Queue operations:

**Insert(int)** insert a positive number, allowed range: [0, u)

**Delete(int)** deletes a previously inserted number

**Succ(int)** finds the next larger number that is already stored inside the tree. Note that the parameter of succ doesn't neet to exist inside the tree. Specially, Succ(-1) gives the minimum (smallest stored element) of the tree.

## Runtime and Space:

All operations run in **O(log log u)** time with u being a large integer provided at initialisation providing an upper limit for the allowed numbers to be inserted.

Space requirement of the (fully filled with all u elements) tree is O(u), as well as initialisation time.

Current implementation uses lazy initialisation, so the init-time is **O(sqrt(u))**, and Insert may run slower until all of the substructures of the tree were used at least once. I might add a switch to toggle both modes at some point in the future.

## Usage:

```

github.com/chucnorrisful/vEB

```

See [test/main.go](test/main.go) for examples.

## Todos:

- [ ] add safety features (member check on insertion, deletion etc.)

- [ ] small optimisations: use bitmasks instead of integer division and mod2 calculations

- [x] add switch for lazyInit vs. fullInit

- [ ] add sparse-mode: usage of hashmaps instead of arrays in internal structure may yield in massive space savings if inserted elements are sparse in a large universe.

- [ ] add linked-list for nodes of tree: enables Succ, Pred in constant time

- [ ] edit PrioQ protocol to also consume Member, Pred, Min, Max

- [ ] extend to negative numbers