Add day 12

1 files changed, 2 insertions, 0 deletions

diff --git a/utils.h b/utils.h
index db6b5de..840d1d4 100644
--- a/utils.h
+++ b/utils.h
@@ -1,6 +1,8 @@
 #ifndef AOC_UTILS_H
 #define AOC_UTILS_H
 
+#define SWAP(a, b) (((a) ^= (b)), ((b) ^= (a)), ((a) ^= (b)))
+
 #define likely(x)       __builtin_expect((x), 1)
 #define unlikely(x)     __builtin_expect((x), 0)