c - 通过编码进行优化

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我有一个素数程序，但我需要优化它。有什么提示吗？

  int num, i, count = 0;

  printf("Type a non-negative integer:\n");

 scanf("%d", &num);

  if((num%2 == 0 )&& (num != 2)||(num == 1)){

    printf("%d is not a prime number.\n", num);

  } else if(num == 2){

    printf("%d is a prime number.\n", num);

  } else {

    for(i = 3; i < num; i += 2){

      if(num%i == 0){

    count++;

    break;

      }

    }

    if(count == 0){

      printf("%d is a prime number.\n", num);

    } else {

      printf("%d is not a prime number.\n", num);

    }

  }

}

Answer 1

您只需检查 num 的平方根即可。请参阅testing primes以获得更多提示。