zoj 2562

反素数+搜索

 1 #include"iostream"
 2 using namespace std;
 3 long long n;
 4 long long maxnum,maxsum;
 5 //当前数,当前第k个因子 ,因子总数,限制
 6 int prime[15]={2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 };
 7 void dfs(long long num,int  k,long long sum,int limit ){
 8     if(sum>maxsum){
 9         maxsum = sum;
10         maxnum = num;
11     }
12     else if(sum==maxsum&&num<maxnum){
13         maxnum = num;
14     }
15     if(k>14)
16         return ;
17     long long temp = num;
18     int i;
19     for(i=1;i<=limit;i++){
20         if(temp*prime[k]>n)
21             break;
22         temp = temp * prime[k];
23         dfs(temp,k+1,sum*(i+1),i);
24     }
25 }
26 int main(){
27     while(cin>>n){
28         maxsum = 0;
29         maxnum = n;
30         dfs(1,0,1,50);
31         cout<<maxnum<<endl;
32     }
33     return 0;
34 }