RosettaCodeData/Task/Ordered-Partitions/GAP/ordered-partitions.gap

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FixedPartitions := function(arg)
local aux;
aux := function(i, u)
local r, v, w;
if i = Size(arg) then
return [[u]];
else
r := [ ];
for v in Combinations(u, arg[i]) do
for w in aux(i + 1, Difference(u, v)) do
Add(r, Concatenation([v], w));
od;
od;
return r;
fi;
end;
return aux(1, [1 .. Sum(arg)]);
end;
FixedPartitions(2, 0, 2);
# [ [ [ 1, 2 ], [ ], [ 3, 4 ] ], [ [ 1, 3 ], [ ], [ 2, 4 ] ],
# [ [ 1, 4 ], [ ], [ 2, 3 ] ], [ [ 2, 3 ], [ ], [ 1, 4 ] ],
# [ [ 2, 4 ], [ ], [ 1, 3 ] ], [ [ 3, 4 ], [ ], [ 1, 2 ] ] ]
FixedPartitions(1, 1, 1);
# [ [ [ 1 ], [ 2 ], [ 3 ] ], [ [ 1 ], [ 3 ], [ 2 ] ], [ [ 2 ], [ 1 ], [ 3 ] ],
# [ [ 2 ], [ 3 ], [ 1 ] ], [ [ 3 ], [ 1 ], [ 2 ] ], [ [ 3 ], [ 2 ], [ 1 ] ] ]