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Re:请问用时很少的同志们是不是素数的判断有什么技巧？指点一下啊！会非常感激的！！！In Reply To:请问用时很少的同志们是不是素数的判断有什么技巧？指点一下啊！会非常感激的！！！ Posted by:fjnu0205046 at 2005-03-14 19:00:24 #include <stdio.h>
#include <memory.h>
bool odd[1000001];
int main()
{
int i, j;
int x;
memset(odd, true, sizeof(odd));
for(i = 2; i <= 500000; i++)
{
if(odd[i])
{
for(j = 2; j < 1000000/i; j++)
{
odd[i + j * i] = false;
}
}
}
scanf("%d", &x);
while(x > 0)
{
for(i = 3; i <= x/2; i += 2)
{
if(odd[i] && odd[x-i])
{
break;
}
}
printf("%d = %d + %d\n", x, i, x-i);
scanf("%d", &x);
}
return 0;
}
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