[Search] n the divisor

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【answer】:

　　Investigation and dfs prime factorisation, to open a first array of prime.

　　Parameters explanation:

　　1, the size of the current value. [N subject to the use of the control range]

　　2, control the lower bound, each time by one prime number to start the search, pos

　　3, the number of control, each time starting from a certain number of primes search.

　　4, the current value of the number of factors.

[Code]:

　　

 1 #include<stdio.h>
 2 #include<algorithm>
 3 using namespace std;
 4 typedef long long ll;
 5 ll prime[ ] = { 0,2,3,5,7,11,
 6                 13,17,19,23,29,
 7                 31,37,41,43,47,
 8                 51};
 9 ll n ;
10 int T;
11 ll dfs( ll num , ll pos ,ll k , ll ans ){
12     if( pos > 15 ) return 0;
13     ll res = ans ;
14     for(int i=1;i<=k;i++){
15         if( n/prime[pos] < num ) break ;
16         num *= prime[pos] ;
17         res = max( res , dfs( num ,pos+1 , i , ans*(i+1) ) );
18     }
19     return res;
20 }
21 int main()
22 {
23     scanf("%d",&T);
24     while(T--){
25         scanf("%lld",&n);
26         ll ans = dfs(1ll,1,64,1);
27         printf("%lld\n",ans);
28     }
29     return 0;
30 }

Submultiple of n