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Implementing prime?(n) and first_primes(n) #6

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Implementing prime?(n) and first_primes(n) #6

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19 changes: 16 additions & 3 deletions week01/1-Warmup-Problems/good_solutions.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -113,11 +113,24 @@ def largest_palindrome(n)
end

def prime?(n)
# Waiting for PR
num = n.to_i.abs

return false if num == 0 || num == 1
2.upto(num - 1) do |i|
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def prime?(n)
  2.upto(n - 1).all? { |i| n % i != 0 }
end

return false if num % i == 0
end

true
end

def list_first_primes(n)
# Waiting for PR
def Integer.all
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Do you really need that?

Enumerator.new do |yielder, n: 0|
loop { yielder.yield(n += 1) }
end.lazy
end

def first_primes(n)
Integer.all.select { |num| prime?(num) && num > 1 }.first(n)
end

def sieve(n)
Expand Down