1 files changed, 9 insertions, 13 deletions
diff --git a/sample/sieve.rb b/sample/sieve.rb
index 03ff8a67f4..e0bb21d640 100644
--- a/sample/sieve.rb
+++ b/sample/sieve.rb
@@ -1,18 +1,14 @@
 # sieve of Eratosthenes
+max = Integer(ARGV.shift || 100)
 sieve = []
-if ! max = ARGV.shift; max = 100; end
-max = max.to_i
+for i in 2 .. max
+  sieve[i] = i
+end
 
-print "1"
-for i in 2 .. max 
-  begin
-    for d in sieve
-      fail if i % d == 0
-    end
-    print ", "
-    print i
-    sieve.push(i)
-  rescue
+for i in 2 .. Math.sqrt(max)
+  next unless sieve[i]
+  (i*i).step(max, i) do |j|
+    sieve[j] = nil
   end
 end
-print "\n"
+puts sieve.compact.join(", ")