p008-consprod.rb

target=7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450
target=target.to_s
maxprod=0
for i in 1..target.length-5
	curprod=Integer(target[i])*Integer(target[i+1])*Integer(target[i+2])*Integer(target[i+3])*Integer(target[i+4])
	if curprod>maxprod ; maxprod=curprod end
end
print maxprod

=begin
originally i was planning on pruning with regex,for example
target.gsub!(/00+/,'0')
target.gsub!(/0[1-9]{1,4}0/,'0')
target.gsub!(/0[1-9]{1,4}0/,'0')
which gets rid of all runs smaller than 4 in between 0s- whose product is 0. this way it would be possible to 
skip ahead by 5 whenever the last digit (target[i+4]) was a 0. apparently this is unnecessary though as this program
runs almost instantly without any pruning
=end