Function malachite_base::slices::exhaustive_slice_permutations

source · [−]

pub fn exhaustive_slice_permutations<T>(
    xs: &[T]
) -> ExhaustiveSlicePermutations<'_, T>ⓘNotable traits for ExhaustiveSlicePermutations<'a, T>impl<'a, T> Iterator for ExhaustiveSlicePermutations<'a, T>    type Item = Vec<&'a T>;

Expand description

Generates every permutation of a slice.

The permutations are Vecs of references into the slice. It may be more convenient for the iterator to own the data, in which case you may use exhaustive_vec_permutations instead.

The permutations are generated in lexicographic order with respect to the ordering in the slice.

The output length is $n!$, where $n$ is xs.len().

Expected complexity per iteration

$T(n) = O(n)$

$M(n) = O(n)$

where $T$ is time, $M$ is additional memory, and $n$ is xs.len().

Examples

extern crate itertools;

use itertools::Itertools;
use malachite_base::slices::exhaustive_slice_permutations;

let css: Vec<String> = exhaustive_slice_permutations(&['a', 'b', 'c', 'd'])
    .map(|ds| ds.into_iter().copied().collect())
    .collect();
assert_eq!(
    css.iter().map(String::as_str).collect_vec().as_slice(),
    [
        "abcd", "abdc", "acbd", "acdb", "adbc", "adcb", "bacd", "badc", "bcad", "bcda", "bdac",
        "bdca", "cabd", "cadb", "cbad", "cbda", "cdab", "cdba", "dabc", "dacb", "dbac", "dbca",
        "dcab", "dcba"
    ]
);