diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/prime.rb | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/lib/prime.rb b/lib/prime.rb index c9575f6a2a..d99a51a967 100644 --- a/lib/prime.rb +++ b/lib/prime.rb @@ -31,7 +31,14 @@ class Integer # Returns true if +self+ is a prime number, else returns false. def prime? - Prime.prime?(self) + return self >= 2 if self <= 3 + return false if self % 2 == 0 or self % 3 == 0 + (5..(self**0.5).floor).step(6).each do |i| + if self % i == 0 || self % (i + 2) == 0 + return false + end + end + true end # Iterates the given block over all prime numbers. |