mationai / binary-indexed-tree-js

Binary Indexed Tree implementation in JavaScript.

Binary Indexed Tree

Binary Indexed Tree(aka Fenwick Tree) implementation

Install

Install with yarn

$ yarn add binary-indexed-tree

Or with npm

$ npm install binary-indexed-tree

BIT?

Binary Indexed Tree (aka Fenwick Tree) is a data structure providing efficient methods for prefix-sum.

API

bit

BinaryIndexedTree implementation

constructor

Parameters

• size number

length

Returns number size of BIT

add

Parameters

• idx number should be less than size of BIT
• val number

Returns boolean successfully added or not O(log(N))

replace

Parameters

• idx number should be less than size of BIT
• val number

Returns boolean successfully replaced or not O(log(N))

original

Parameters

• idx number should be less than size of BIT

Returns number original value of array O(log(N))

get

Parameters

• idx number should be less than size of BIT

Returns number sum of range [0..idx] O(log(N))

prefix

Parameters

• idx number should be less than size of BIT

Returns number sum of range [0..idx) O(log(N))

sum

Returns number sum of all O(log(N))

find

linear search.

Parameters

• check Function function

Returns number value of first target, or undefined O(N * log(N))

findIndex

linear search.

Parameters

• check Function function

Returns number index of first target, or -1 O(N * log(N))

indexOf

linear search.

Parameters

• target number value
• equal [Function] equality function

Returns number index of first target, or -1 O(N * log(N))

lastIndexOf

linear search.

Parameters

• target number value
• equal [Function] equality function

Returns number index of last target, or -1 O(N * log(N))

lowerBound

find lower bound. SEQUENCE SHOULD BE INCREASING IN ORDER (GIVEN BY COMPERATOR). IF ANY ITEM HAS MINUS VALUE, THIS METHOD WILL NOT WORK.

Parameters

• target number
• comp [Function]

Returns number index of lower-bound O(log(N))

upperBound

find upper bound. SEQUENCE SHOULD BE INCREASING IN ORDER (GIVEN BY COMPERATOR). IF ANY ITEM HAS MINUS VALUE, THIS METHOD WILL NOT WORK.

Parameters

• target number
• comp [Function]

Returns number index of upper-bound O(log(N))

toArray

Returns Array<number> array of cusum O(N)

build

Parameters

• seed Array<number> BIT will be built from this array

Returns BinaryIndexedTree instance O(N)

Changelog

Read the CHANGELOG.

Running tests

Install devDependencies and Run npm test or yarn test

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request :D

License

Copyright © 2016-present berlysia. Licensed under the MIT license.