HDU 4135 Co-prime

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long LL;
 4 vector<LL>g;
 5 LL solve(LL x,LL y) {
 6     g.clear();
 7     for(LL i = 2; i*i <= y; ++i) {
 8         if(y%i == 0) {
 9             while(y%i == 0) y /= i;
10             for(int j = g.size()-1; j >= 0; --j)
11                 if(abs(i*g[j] <= x)) g.push_back(-i*g[j]);
12             g.push_back(i);
13         }
14     }
15     if(y > 1) {
16         for(int i = g.size()-1; i >= 0; --i)
17             if(abs(y*g[i]) <= x) g.push_back(-y*g[i]);
18         g.push_back(y);
19     }
20     LL ret = 0;
21     for(int i = g.size()-1; i >= 0; --i) ret += x/g[i];
22     return x - ret;
23 }
24 int main() {
25     int t,cs = 1;
26     LL a,b,n;
27     scanf("%d",&t);
28     while(t--){
29         scanf("%I64d%I64d%I64d",&a,&b,&n);
30         printf("Case #%d: %I64d\n",cs++,solve(b,n) - solve(a-1,n));
31     }
32     return 0;
33 }