Function sorted_iter::multiway_union

pub fn multiway_union<T, I>(iters: T) -> MultiwayUnion<I> where
    I: SortedIterator,
    T: IntoIterator<Item = I>,
    I::Item: Ord, 

Union of multiple sorted iterators.

An advantage of this function over multiple calls to SortedIterator::union is that the number of merged sequences does not need to be known at the compile time. The drawback lies in the fact that all iterators have to be of the same type.

The algorithmic complexity of fully consuming the resulting iterator is O(N log(K)) where N is the total number of items that the input iterators yield and K is the number of input iterators.

Examples

use sorted_iter::multiway_union;

let sequences = vec![
    btreeset! { 0, 5, 10, 15, 20, 25 }.into_iter(),
    btreeset! { 0, 1, 4, 9, 16, 25, 36 }.into_iter(),
    btreeset! { 4, 7, 11, 15, 18 }.into_iter(),
];

assert_eq!(
    multiway_union(sequences).collect::<BTreeSet<u64>>(),
    btreeset! { 0, 1, 4, 5, 7, 9, 10, 11, 15, 16, 18, 20, 25, 36 }
);