Problem 7--(c)

Problem 7

28 December 2001

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6^th prime is 13.

What is the 10001^st prime number?

Answer:

104743

code:
#include
#include

int primer(long int n)
{
int flag=1;
long int i;
for(i=2;i<=sqrt(n)&&flag==1;i++)
if(n%i==0)
flag=0;
return (flag);
}

int main(void)
{
long int a[10001],num=3,i=1;/*忽略了2，这种情况，第10000，就是所求*/
while(i<=10000)
{
if(primer(num))
{
a[i]=num;
i++;
}
num=num+2;
}
printf("%ld\n",a[10000]);
return 0;
}