PAT_1007(中文)_素数对猜想

题目地址：http://pat.zju.edu.cn/contests/pat-b-practise/1007

#include<stdio.h>
#include<math.h>

int i, j;
int num[100005];
int n;
int count = 0;
int temp = 0;
int main()
{
    scanf("%d", &n);
    num[0] = 2;
    num[1] = 3;
    count = 2;
    for( i = 4; i <= n; ++i )
    {
        temp = 0;
        for( j = 2; j <= sqrt(i); ++j )
        {
            if( (i % j) == 0 )
            {
                temp = 1;
                break;
            }
        }
        if( temp != 1 )
        {
            num[count] = i;
            ++count;
        }
    }
    temp = 0;
    for( i = 0; i < count - 1; ++i )
    {
        if( (num[i+1] - num[i]) == 2 )
            ++temp;
    }
    printf("%d\n", temp);
    return 0;
}