洛谷P2257_YY的GCD

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

int tt=1e7,n,m,mu[(int)1e7+9],s[(int)1e7+9],pr[(int)1e7+9],cnt;
bitset<(int)1e7+9>vis;

void init(int x){
    mu[1]=1;
    for(ll i=2;i<=x;++i){
        if(!vis[i])pr[++cnt]=i,mu[i]=-1;
        for(int j=1;j<=cnt&&i*pr[j]<=x;++j){
            vis[pr[j]*i]=1;
            if(i%pr[j]==0)break;
            mu[i*pr[j]]=-mu[i];
        }
    }
    for(int i=1;i<=cnt;++i)for(ll j=1;j*pr[i]<=x;++j)s[j*pr[i]]+=mu[j];
    for(int i=1;i<=x;++i)s[i]+=s[i-1];
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    init(tt);
    cin>>tt;
    f(S,1,tt){
        cin>>n>>m;
        if(n>m)swap(n,m);
        ll ans=0;
        for(int l=1,r;l<=n;l=r+1){
            r=min(n/(n/l),m/(m/l));
            ans+=1ll*(n/l)*(m/l)*(s[r]-s[l-1]);
        }
        cout<<ans<<"\n";
    }
    return 0;
}