Function malachite_base::sets::exhaustive::exhaustive_hash_sets_min_length

source · [−]

pub fn exhaustive_hash_sets_min_length<I: Clone + Iterator>(
    min_length: u64, 
    xs: I
) -> ExhaustiveOrderedUniqueCollections<I, HashSet<I::Item>>ⓘNotable traits for ExhaustiveOrderedUniqueCollections<I, C>impl<I: Iterator, C: FromIterator<I::Item>> Iterator for ExhaustiveOrderedUniqueCollections<I, C> where
    I::Item: Clone,     type Item = C; where
    I::Item: Clone + Eq + Hash,

Expand description

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

extern crate itertools;
#[macro_use]
extern crate maplit;

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

fn main() {
    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}
        ]
    );
}