Created
July 10, 2016 00:55
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Prime
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| boolean isPrime(int n) { | |
| if(n < 2) return false; | |
| for(int i = 2; i <= Math.sqrt(n); ++i) { | |
| if(n % i == 0) return false; | |
| } | |
| return true; | |
| } |
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The square root of n is sufficient because, for every number a which divides n evenly, there is a complement b, where a *b = n. I fa > sqrt(n), then b < sqrt(n) (since(sqrt(n))^2 = n).We therefore don't need a to check n's primality, since we would have already checked with b.