Puzzle 19: Don't do nothing if we could build all robots.

The only reason to do nothing would be to save resources to build a
robot we can't affort to build yet. But if we have enough resources to
build all of them, there's no point in not building any

Drops time by 35% on full 24-round test data (7.2s -> 4.6s)

1 files changed, 13 insertions, 5 deletions

diff --git a/19.c b/19.c
index cccc746..2700712 100644
--- a/19.c
+++ b/19.c
@@ -228,14 +228,22 @@ inventory_build_exhaustive(struct inventory * i, struct blueprint const * b, int
 
 	++exhaustive_iter;
 
-	// Try doing nothing else this round.
 	best = *i;
-	inventory_tick(&best);
-//	fprintf(stderr, "%d: doing nothing\n", remaining);
-	inventory_build_exhaustive(&best, b, remaining - 1);
-
 	test = *i;
 
+	// If there are some robots we can't build yet, try doing nothing this round.
+	if (i->ore.amount < b->max_ore
+			|| i->clay.amount < b->max_clay
+			|| i->bsdn.amount < b->max_bsdn)
+	{
+		inventory_tick(&test);
+//		fprintf(stderr, "%d: doing nothing\n", remaining);
+		inventory_build_exhaustive(&test, b, remaining - 1);
+		if (inventory_cmp(&test, &best) > 0)
+			best = test;
+		test = *i;
+	}
+
 	// Try building a geode robot, and check if that's better than doing nothing.
 	if (inventory_build(&test, b, GEOD) == 0) {
 //		fprintf(stderr, "%d: building a geod robot (%ld)\n", remaining, test.geod.amount);