permutations method

Iterable<Iterable<T>> permutations()

Returns an iterable that consists of iterables, where each iterable is a collection of all the permutations of the elements in this iterable.

Example:

void main() {
  final list = [1, 2, 3];
  final result = list.permutations();

  // Result: [
  //   [1, 2, 3],
  //   [2, 1, 3],
  //   [3, 1, 2],
  //   [1, 3, 2],
  //   [2, 3, 1],
  //   [3, 2, 1],
  // ]
}

Note: For reasons of efficiency and consistency across iterations, the returned iterable is implicitly memoized.

Implementation

Iterable<Iterable<T>> permutations() {
  final tempList = toList();
  return _permutationsRecursive(tempList, tempList.length, tempList.length)
      .memoize();
}