1.3 KiB
1.3 KiB
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5900f4371000cf542c50ff49 | Problem 202: Laserbeam | 5 | 301843 | problem-202-laserbeam |
--description--
Three mirrors are arranged in the shape of an equilateral triangle, with their reflective surfaces pointing inwards. There is an infinitesimal gap at each vertex of the triangle through which a laser beam may pass.
Label the vertices A
, B
and C
. There are 2 ways in which a laser beam may enter vertex C
, bounce off 11 surfaces, then exit through the same vertex: one way is shown below; the other is the reverse of that.
There are 80840 ways in which a laser beam may enter vertex C
, bounce off 1000001 surfaces, then exit through the same vertex.
In how many ways can a laser beam enter at vertex C
, bounce off 12017639147 surfaces, then exit through the same vertex?
--hints--
laserbeam()
should return 1209002624
.
assert.strictEqual(laserbeam(), 1209002624);
--seed--
--seed-contents--
function laserbeam() {
return true;
}
laserbeam();
--solutions--
// solution required