From: Neil Smith <neil.git@njae.me.uk>
Date: Thu, 16 Feb 2017 14:04:29 +0000 (+0000)
Subject: Made the primes library faster
X-Git-Url: https://git.njae.me.uk/?a=commitdiff_plain;h=46afc3b90a7bed5b5a44f812c631949edd23307c;p=project-euler.git

Made the primes library faster
---

diff --git a/euler35.rb b/euler35.rb
index ebe8450..d2ba75d 100644
--- a/euler35.rb
+++ b/euler35.rb
@@ -36,10 +36,11 @@ class Integer
 end 
 
 
-(10**6).prime?
-
 RubyProf.start
 
+# (10**6).prime?
+
+
 pl0 = 0.pl
 beginning_time = Time.now
 cps = (2..10**6).select {|n| n.circular_prime?}
diff --git a/primes.rb b/primes.rb
index 0febe80..23fd447 100644
--- a/primes.rb
+++ b/primes.rb
@@ -28,7 +28,9 @@ class Primes
 
   def next_prime
     candidate = next_candidate(@primes[-1])
-    while @primes.any? {|i| candidate % i == 0 }
+    limit = Math.sqrt(candidate).floor
+    index = @primes.bsearch_index {|i| i > limit} || @primes.length
+    while @primes[0..index].any? {|i| candidate % i == 0 }
       candidate = next_candidate(candidate)
     end
     candidate
@@ -90,10 +92,11 @@ class Primes
   end
   
   def include?(n)
-    while n >= @primes.max
+    while n >= @primes.last
       add_next_prime!
     end
-    @primes.include?(n)
+    # @primes.include?(n)
+    !!(@primes.bsearch {|i| n - i})
   end
 
 end