LCM Cardinality UVA - 10892

给出n, 求有多少对(a,b) (a<b), 满足 LCM(a,b) =n

 

暴力求所有因数

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
const int N =1e4+20;
#define int long long
const int inf =1e9 ;
 
 void sov(int n){
 	vector<int>v;
 	int i,j;
 	if(n==1){ cout<<1<<' '<<1<<endl; return ; }
 	
 	for(i=2;i*i<=n;i++)
 		if(n%i==0){
 			v.push_back(i); if(i*i!=n) v.push_back(n/i); 
 		}
 	v.push_back(n); v.push_back(1);
 	
 	int ans=0;
 	sort(v.begin(),v.end());
 	for(i=0;i<v.size();i++)
 	 for(j=i;j<v.size();j++){
 	 	int x=v[i],y=v[j];
 	 	if(x/__gcd(x,y)*y==n){
 	 		ans++;
 	 	}
 	 }
 	cout << n<<' '<<ans<<endl;
 }
 signed main(){
 	int n;while(cin>>n&&n) sov(n);
 }