Make sure the sum of weights is positive to avoid undefined behavior

1 files changed, 3 insertions, 0 deletions

diff --git a/sd.c b/sd.c
index 7d00989..cd8195d 100644
--- a/sd.c
+++ b/sd.c
@@ -59,6 +59,9 @@ int main(int argc, char* argv[]) {
 	assert(system("stty -F /dev/tty -echo") == 0);
 
 	while (true) {
+		/* Make sure sum of weights is positive */
+		assert(seg[1] > 0);
+
 		int x = (long long)rand() * rand() % seg[1];
 		int res[2];
 		query(res, x, 0, N-1, 1);