2
25608
24027

7680
16016
我的超时了~
#include<iostream>
#include<stdio.h>
#include<math.h>
#include<string.h>
using namespace std;
int gcd(int a,int b)
{
    if(b==0)
      return a;
    return gcd(b,a%b);
}
int main()
{
    int T,n,i,count;
    cin>>T;
    while(T--)
    {
        count=0;
        cin>>n; 
        for(i=2;i<n;i++)
         { 
           if(gcd(i,n)>1)
            count++;
         }     
     cout<<(n-count-1)<<endl;
    }
 return 0;
}
看了一个大神的博客，感觉写的很好。
http://www.cnblogs.com/chuanlong/archive/2012/10/18/2728893.html
<pre name="code" class="cpp">#include <stdio.h>
#include <string>
#define MAXN 32768
int a[MAXN + 5];
int main()
{
    int i, j, k, CN, num, count;
    scanf("%d", &CN);
    while (CN--)
    {
        //initialize the array
        memset(a, 0, sizeof(a));
        scanf("%d", &num);
        //if the number have common divisor with the input, make the value = 1
        for (j = 2; j < num; j++)        
            if (num % j == 0)
                for (k = j; k < num; k += j)
                    a[k] = 1;
        count = 0;
        //numbers of zero is numbers of new friends, pay attention to k = 1
        for (k = 1; k < num; k++)
            if (a[k] == 0)
                count++;
        printf("%d\n", count);
    }
}