There was a TODO about quadratic performance, and indeed,
it can get bad. Added a map, made some integers that are
unlikely to exceed a few million into 32-bit integers.
Change-Id: I6facf2eabc00483e943b326ca8dcae2f778093da
Reviewed-on: https://go-review.googlesource.com/c/go/+/422297
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>