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def populate_array(n)
arr = Array.new(n, true)
arr[0] = false
arr[1] = false
arr
end
def print_array(a)
count = 0
while count < a.length
puts "#{count} is prime" if a[count]
count += 1
end
end
def mark_factors(a, count)
mult = 2
while count * mult <= a.length
a[count * mult] = false
mult += 1
end
a
end
def sieve(a)
count = 2
while count <= Math.sqrt(a.length)
a = mark_factors(a, count) if a[count]
count += 1
end
end
def main
puts 'Give me the limit for your primes'
n = Integer(gets.chomp)
a = populate_array(n + 1)
sieve(a)
print_array(a)
end
main
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