Created
May 28, 2018 20:25
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| func sieve(numbers: [Int]) -> [Int] { | |
| if numbers.isEmpty { return [] } | |
| let p = numbers[0] | |
| // assert(p > 1, "numbers must start at 2 or higher") | |
| let rest = numbers[1..<numbers.count] | |
| return [p] + sieve(rest.filter { $0 % p > 0 }) | |
| } | |
| func primesUpTo(max: Int) -> [Int] { | |
| return [1] + sieve(Array(2...max)) | |
| } |
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