Function malachite_base::sets::exhaustive::exhaustive_hash_sets_min_length

pub fn exhaustive_hash_sets_min_length<I: Clone + Iterator>(
    min_length: u64,
    xs: I,
) -> ExhaustiveOrderedUniqueCollections<I, HashSet<I::Item>> 
where
    I::Item: Clone + Eq + Hash,

Generates HashSets with a mininum length, with elements from a single 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 $n$ and the min_length is $\ell$, the output length is $$ \sum_{i=\ell}^n \binom{n}{i}. $$

Examples

use itertools::Itertools;
use malachite_base::sets::exhaustive::exhaustive_hash_sets_min_length;
use maplit::hashset;

let xss = exhaustive_hash_sets_min_length(2, 1..=4).collect_vec();
assert_eq!(
    xss,
    &[
        hashset! {1, 2},
        hashset! {1, 3},
        hashset! {2, 3},
        hashset! {1, 2, 3},
        hashset! {1, 4},
        hashset! {2, 4},
        hashset! {1, 2, 4},
        hashset! {3, 4},
        hashset! {1, 3, 4},
        hashset! {2, 3, 4},
        hashset! {1, 2, 3, 4}
    ]
);