Function malachite_base::sets::exhaustive::exhaustive_hash_sets_length_range
source · pub fn exhaustive_hash_sets_length_range<I: Clone + Iterator>(
a: u64,
b: u64,
xs: I
) -> ExhaustiveOrderedUniqueCollections<I, HashSet<I::Item>> ⓘ
Expand description
Generates HashSet
s, with lengths in a range $[a, b)$, 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 $a \leq b$, the output is empty.
If $a = 0$ and $b = 1$, the output consists of a single empty HashSet
.
If the input iterator is infinite and $0 < a < b$, the output length is also infinite.
If the input iterator length is $n$, the output length is $$ \sum_{i=a}^b - 1 \binom{n}{i}. $$
§Examples
#[macro_use]
extern crate maplit;
use itertools::Itertools;
use malachite_base::sets::exhaustive::exhaustive_hash_sets_length_range;
fn main() {
let xss = exhaustive_hash_sets_length_range(2, 4, 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}
]
);
}