bzoj2820: YY的GCD

链接：http://www.lydsy.com/JudgeOnline/problem.php?id=2820

题意：中文题。。。

分析：同bzoj2301，论文题。

代码：

#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<math.h>
#include<cstdio>
#include<vector>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
#pragma comment(linker, "/STACK:102400000,102400000")
using namespace std;
const int N=10000010;
const int MAX=151;
const int MOD=1000000007;
const int MOD1=100000007;
const int MOD2=100000009;
const int INF=2100000000;
const double EPS=0.00000001;
typedef long long ll;
typedef unsigned long long uI64;
int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int a[N],bo[N],mu[N],su[N];
ll sum[N];
void deal() {
    int i,j,k,w,n=10000000;
    memset(bo,0,sizeof(bo));
    mu[1]=1;sum[0]=k=0;
    for (i=2;i<=n;i++) {
        if (!bo[i]) { a[++k]=i;mu[i]=-1; }
        for (j=1;j<=k;j++) {
            if (a[j]*i>n) break ;
            bo[a[j]*i]=1;
            if (i%a[j]==0) { mu[a[j]*i]=0;break ; }
            mu[a[j]*i]=-mu[i];
        }
    }
    memset(su,0,sizeof(su));
    for (i=1;i<=k;i++) {
        w=a[i];
        while (w<=n) { su[w]+=mu[w/a[i]];w+=a[i]; }
    }
    for (i=1;i<=n;i++) sum[i]=sum[i-1]+su[i];
}
ll get(int n,int m) {
    ll ret=0;
    int i,last;
    if (n>m) { n^=m;m^=n;n^=m; }
    for (i=1;i<=n;i=last+1) {
        last=min(n/(n/i),m/(m/i));
        ret+=(ll)(n/i)*(m/i)*(sum[last]-sum[i-1]);
    }
    return ret;
}
int main()
{
    int n,m,t;
    scanf("%d", &t);
    deal();
    while (t--) {
        scanf("%d%d", &n, &m);
        printf("%lld\n", get(n,m));
    }
    return 0;
}

/*
10
10 10
100 100
*/