优化代码

算法/数学/质数.c

@@ -4,11 +4,13 @@
 
 bool prime(unsigned natural)
 {
-	if (natural <= 1)
+	if (natural == 2)
+		return true;
+	if (natural < 2 || natural % 2 == 0)
 		return false;
-	for (unsigned factor = 2, \
+	for (unsigned factor = 3, \
 		limit = (unsigned)floor(sqrt(natural)); \
-		factor <= limit; ++factor)
+		factor <= limit; factor += 2)
 		if (natural%factor == 0)
 			return false;
 	return true;