GiST/GIN index for field of type VARCHAR[]

I have following table:
CREATE TABLE t1 (
"name" VARCHAR(500) NOT NULL,
"lid" INTEGER NOT NULL,
"accs" VARCHAR(20)[] NOT NULL
CONSTRAINT "t1_lid_key" UNIQUE("lid")
);

I interested in the possibility to speed-up search for rows like this:
SELECT lid
FROM t1
WHERE accs && ARRAY['item1','item2'...]::VARCHAR[];

For sure, I can use the typical way of data normalization to decrease
query time:
CREATE TABLE t2(
"lid" INTEGER NOT NULL,
"acc" VARCHAR(20) NOT NULL
);
with: t2.lid = t1.lid & t1.accs @> ARRAY[t2.acc]
and create hash index on acc.

Then I could SELECT lid FROM t2 WHERE acc IN(item1,item2);

But it's more interesting to implement GiST/GIN indexes for this purpose.
And what type of index is the most suitable if VARCHAR[] arrays are
1-dimensional and contain from 1 to 20000 elements?

Thanks in advance.

--
Best regards. Yuri.
mailto: yuragal(at)gmail(dot)com