Function malachite_base::sets::exhaustive::exhaustive_hash_sets_fixed_length

source · [−]

pub fn exhaustive_hash_sets_fixed_length<I: Clone + Iterator>(
    k: 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 of a given size with elements from a single iterator.

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

If $k$ is 0, the output length is 1.

If $k$ is nonzero and the input iterator is infinite, the output length is also infinite.

If $k$ is nonzero and the input iterator length is $n$, the output length is $\binom{n}{k}$.

If $k$ is 0, the output consists of one empty HashSet.

If xs is empty, the output is also empty, unless $k$ is 0.

Examples

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

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

fn main() {
    let xss = exhaustive_hash_sets_fixed_length(4, 1..=6).collect_vec();
    assert_eq!(
        xss,
        &[
             hashset!{1, 2, 3, 4},
             hashset!{1, 2, 3, 5},
             hashset!{1, 2, 4, 5},
             hashset!{1, 3, 4, 5},
             hashset!{2, 3, 4, 5},
             hashset!{1, 2, 3, 6},
             hashset!{1, 2, 4, 6},
             hashset!{1, 3, 4, 6},
             hashset!{2, 3, 4, 6},
             hashset!{1, 2, 5, 6},
             hashset!{1, 3, 5, 6},
             hashset!{2, 3, 5, 6},
             hashset!{1, 4, 5, 6},
             hashset!{2, 4, 5, 6},
             hashset!{3, 4, 5, 6}
        ]
    );
}