Predicate the given ranges are sorted by.
A range of ranges sorted by less to compute the intersection for.
A range of the union of the ranges in ror.
See also: multiwayMerge
import std.algorithm.comparison : equal; // sets double[][] a = [ [ 1, 4, 7, 8 ], [ 1, 7 ], [ 1, 7, 8], [ 4 ], [ 7 ], ]; auto witness = [1, 4, 7, 8]; assert(equal(multiwayUnion(a), witness)); // multisets double[][] b = [ [ 1, 1, 1, 4, 7, 8 ], [ 1, 7 ], [ 1, 7, 7, 8], [ 4 ], [ 7 ], ]; assert(equal(multiwayUnion(b), witness)); double[][] c = [ [9, 8, 8, 8, 7, 6], [9, 8, 6], [9, 8, 5] ]; auto witness2 = [9, 8, 7, 6, 5]; assert(equal(multiwayUnion!"a > b"(c), witness2));
Computes the union of multiple ranges. The input ranges are passed as a range of ranges and each is assumed to be sorted by less. Computation is done lazily, one union element at a time. multiwayUnion(ror) is functionally equivalent to multiwayMerge(ror).uniq.
"The output of multiwayUnion has no duplicates even when its inputs contain duplicates."