Function malachite_base::sets::exhaustive::lex_b_tree_sets

pub fn lex_b_tree_sets<I: Clone + Iterator>(
    xs: I
) -> LexOrderedUniqueCollections<I, BTreeSet<I::Item>> where
    I::Item: Clone + Ord,

Generates BTreeSets with elements from a single iterator.

The BTreeSets are ordered lexicographically with respect to the order of the element iterator.

The source iterator should not repeat any elements, but this is not enforced.

The iterator should be finite; if it is infinite, only prefixes of the iterator will be generated.

If the input iterator is infinite, the output length is also infinite.

If the input iterator length is $n$, the output length is $2^n$.

If xs is empty, the output consists of a single empty BTreeSet.

Examples

#[macro_use]
extern crate maplit;

use itertools::Itertools;
use malachite_base::sets::exhaustive::lex_b_tree_sets;

fn main() {
    let xss = lex_b_tree_sets(1..=4).collect_vec();
    assert_eq!(
        xss,
        &[
            btreeset!{},
            btreeset!{1},
            btreeset!{1, 2},
            btreeset!{1, 2, 3},
            btreeset!{1, 2, 3, 4},
            btreeset!{1, 2, 4},
            btreeset!{1, 3},
            btreeset!{1, 3, 4},
            btreeset!{1, 4},
            btreeset!{2},
            btreeset!{2, 3},
            btreeset!{2, 3, 4},
            btreeset!{2, 4},
            btreeset!{3},
            btreeset!{3, 4},
            btreeset!{4}
        ]
    );
}