Oops! This was left over from an early development version of commits
4408476b7 and
000ebc507, in which I initially arranged for each
adjacency list to be terminated with the sentinel value -1 instead of
separately storing an array of the lists' lengths.
I later changed the representation to make randomising the algorithm
easier (it's much easier to shuffle an array uniformly at random if
you _don't_ have to faff endlessly to work out its length). But this
write of a no-longer- needed sentinel value in the client code must
have survived the rewrite by mistake, and also somehow evaded all my
pre-commit testing with valgrind and asan.
A user reported that the Towers Javascript version was crashing on
startup, and I think this is the cause, because it seems to fix it for
me.
if (adj[k])
*p++ = k;
adjsizes[j] = p - adjlists[j];
- *p = -1;
}
/*