hdu 2841 Visible Trees

 /**
 大意： 求[1，m]， [1，n]  之间有多少个数互素。。。做了 1695 ，，这题就so easy 了
 **/
 #include <iostream>
 #include <cmath>
 #include <algorithm>
 using namespace std;
 const long long  maxn = ;
 long long phi[maxn];
 long long priD[maxn];
 int len ;

 void euler(long long  n){
     long long  m = (int )sqrt(n+0.5);
     len =;
     for(int i=;i<=m;i++)if(n%i==){
         priD[len++] = i;
         while(n%i==)
             n = n/i;
     }
     if(n>)
         priD[len++] = n;
 }

 void phi_table(){
     for(int i=;i<maxn;i++)
         phi[i] =;
     phi[] =;
     for(int i=;i<maxn;i++)if(!phi[i]){
         for(int j=i;j<maxn;j+=i){
             if(!phi[j]) phi[j] =j;
             phi[j] = phi[j]/i*(i-);
         }
     }
 }

 long long solve(long long  m){
     long long  sum = ;
     long long  flag,tmp;
     for(int i=;i<1ll<<len;i++){
         tmp =;
         flag =;
         for(int j=;j<len;j++){
             if(i&(1ll<<j)){
                 tmp *= priD[j];
                 flag++;
             }
         }
         if(flag%)
             sum += m/tmp;
         else
             sum -= m/tmp;
     }
     return sum;
 }

 int main()
 {
     phi_table();
     int t;
     cin>>t;
     long long  n,m;
     while(t--){
         cin>>m>>n;
         if(m>n) //我们先默认 n > m， 不符合交换
             swap(n,m);
         long long sum =;
         for(int i=;i<=m;i++)
             sum += phi[i];
         sum = sum*-;
         for(int i=m+;i<=n;i++){
             euler(i);
             sum += (m-solve(m));
         }
         cout<<sum<<endl;
     }
     return ;
 }