All combinations of a list in Dart

Question

I need the classic N choose K algorithm to generate all the possible combinations of a list or iterable in Dart. Is there any implementation out there?

Something like https://pub.dartlang.org/packages/trotter? – Günter Zöchbauer Mar 31 '15 at 19:03 — Günter Zöchbauer, Mar 31 '15 at 19:03
Sounds perfect! Why don't you post the answer? – Cristian Garcia Apr 06 '15 at 15:26 — Cristian Garcia, Apr 06 '15 at 15:26

score 7 · Answer 1 · answered Apr 06 '15 at 15:27

7

The package trotter seems to do what you are looking for.

answered Apr 06 '15 at 15:27

Günter Zöchbauer

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even through it looks cool, it doesn't have null safety as for Sept 1 2021 – goodniceweb Sep 01 '21 at 06:39
1

Any null-safety solution? – genericUser Mar 18 '22 at 11:22
1

@goodniceweb checkout this solution https://stackoverflow.com/a/64302098/12695188 – genericUser Mar 18 '22 at 11:30

Mike Knapp · Answer 2 · 2022-08-28T01:19:07.903

There is now an unreleased null safety version of trotter. Add the following dependency to your pubspec.yaml:

trotter: ^2.0.0-dev.1

Then you can do something like this:

var c = Combinations(3, characters('abcd'));
print('There are ${c.length} 3-combinations of the objects');
print('in ${c.items}.');
print('The first combination is ${c[0]}.');

You can make a Combinations object for a custom type as well:

var c = Combinations<MyType>(3, [obj1, obj2]);

All combinations of a list in Dart

2 Answers2