https://github.com/mxschmitt/golang-combinations

Golang library which provide an algorithm to generate all combinations out of a given string array.
https://github.com/mxschmitt/golang-combinations

arrangement array golang hacktoberfest permutation powerset string strings

Last synced: about 2 months ago
JSON representation

Golang library which provide an algorithm to generate all combinations out of a given string array.

• Host: GitHub
• URL: https://github.com/mxschmitt/golang-combinations
• Owner: mxschmitt
• License: mit
• Created: 2018-05-28T21:34:57.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2024-05-19T17:47:36.000Z (4 months ago)
• Last Synced: 2024-06-18T14:00:13.232Z (3 months ago)
• Topics: arrangement, array, golang, hacktoberfest, permutation, powerset, string, strings
• Language: Go
• Homepage: https://mxschmitt.github.io/golang-combinations
• Size: 30.3 KB
• Stars: 111
• Watchers: 6
• Forks: 19
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

Awesome Lists containing this project

README

        
# Golang combinations

[![GoDoc](https://godoc.org/github.com/mxschmitt/golang-combinations?status.svg)](https://godoc.org/github.com/mxschmitt/golang-combinations)

[![Go](https://github.com/mxschmitt/golang-combinations/actions/workflows/go.yml/badge.svg)](https://github.com/mxschmitt/golang-combinations/actions/workflows/go.yml)

[![Coverage Status](https://coveralls.io/repos/github/mxschmitt/golang-combinations/badge.svg?branch=master)](https://coveralls.io/github/mxschmitt/golang-combinations?branch=master)

[![Go Report Card](https://goreportcard.com/badge/github.com/mxschmitt/golang-combinations)](https://goreportcard.com/report/github.com/mxschmitt/golang-combinations)

[![License](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)

This package provides a method to generate all ordered combinations out of a given generic array.

This essentially creates the powerset of the given array except that the empty set is disregarded.

## Examples

Take a look at the [godoc](https://godoc.org/github.com/mxschmitt/golang-combinations/#pkg-examples) for examples.

In general when you have e.g. `[]string{"A", "B", "C"}` you will get:

```json

[

    ["A"],

    ["B"],

    ["A", "B"],

    ["C"],

    ["A", "C"],

    ["B", "C"],

    ["A", "B", "C"]

]

```

## Background

The algorithm iterates over each number from `1` to `2^length(input)`, separating it by binary components and utilizes the true/false interpretation of binary 1's and 0's to extract all unique ordered combinations of the input slice.

E.g. a binary number `0011` means selecting the first and second index from the slice and ignoring the third and fourth. For input `{"A", "B", "C", "D"}` this signifies the combination `{"A", "B"}`.

For input slice `{"A", "B", "C", "D"}` there are `2^4 - 1 = 15` binary combinations, so mapping each bit position to a slice index and selecting the entry for binary `1` and discarding for binary `0` gives the full subset as:

```txt

1	=	0001	=>	---A	=>	{"A"}

2	=	0010	=>	--B-	=>	{"B"}

3	=	0011	=>	--BA	=>	{"A", "B"}

4	=	0100	=>	-C--	=>	{"C"}

5	=	0101	=>	-C-A	=>	{"A", "C"}

6	=	0110	=>	-CB-	=>	{"B", "C"}

7	=	0111	=>	-CBA	=>	{"A", "B", "C"}

8	=	1000	=>	D---	=>	{"D"}

9	=	1001	=>	D--A	=>	{"A", "D"}

10	=	1010	=>	D-B-	=>	{"B", "D"}

11	=	1011	=>	D-BA	=>	{"A", "B", "D"}

12	=	1100	=>	DC--	=>	{"C", "D"}

13	=	1101	=>	DC-A	=>	{"A", "C", "D"}

14	=	1110	=>	DCB-	=>	{"B", "C", "D"}

15	=	1111	=>	DCBA	=>	{"A", "B", "C", "D"}

```