22 lines
249 B
C
22 lines
249 B
C
int is_prime(long num)
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{
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int i = 5;
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int w = 2;
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if (num == 1)
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return 0;
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if (num == 2 || num == 3)
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return 1;
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if (!(num%2) || !(num%3))
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return 0;
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while ((i*i) <= num) {
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if (!(num%i))
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return 0;
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i += w;
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w = 6 - w;
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}
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return 1;
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}
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