BZOJ2820: YY的GCD

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<iostream>
 7 #include<vector>
 8 #include<map>
 9 #include<set>
10 #include<queue>
11 #include<string>
12 #define inf 1000000000
13 #define maxn 10000000+5
14 #define maxm 100000+5
15 #define eps 1e-10
16 #define ll long long
17 #define pa pair<int,int>
18 #define for0(i,n) for(int i=0;i<=(n);i++)
19 #define for1(i,n) for(int i=1;i<=(n);i++)
20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
22 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)
23 #define mod 1000000007
24 using namespace std;
25 inline int read()
26 {
27     int x=0,f=1;char ch=getchar();
28     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
29     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
30     return x*f;
31 }
32 int tot,p[maxn],mu[maxn];
33 ll g[maxn];
34 bool v[maxn];
35 void get()
36 {
37     mu[1]=1;
38     for2(i,2,10000000)
39     {
40         if(!v[i])p[++tot]=i,mu[i]=-1,g[i]=1;
41         for1(j,tot)
42         {
43             int k=i*p[j];
44             if(k>10000000)break;
45             v[k]=1;
46             if(i%p[j])mu[k]=-mu[i],g[k]=mu[i]-g[i];
47             else {mu[k]=0;g[k]=mu[i];break;}
48         }
49     }
50     for1(i,10000000)g[i]+=g[i-1];
51 }
52 int main()
53 {
54     freopen("input.txt","r",stdin);
55     freopen("output.txt","w",stdout);
56     get();
57     int T=read();
58     while(T--)
59     {
60         ll n=read(),m=read(),ans=0;
61         if(n>m)swap(n,m);
62         for(int i=1,pos;i<=n;i=pos+1)
63         {
64             pos=min(n/(n/i),m/(m/i));
65             ans+=(g[pos]-g[i-1])*(n/i)*(m/i);
66         }
67         printf("%lld\n",ans);
68     }        
69     return 0;
70 }