bzoj千题计划296：bzoj1053: [HAOI2007]反素数ant

http://www.lydsy.com/JudgeOnline/problem.php?id=1053

 

求n以内约数个数最多的数

 

#include<cstdio>

using namespace std;

int n;

int ans;
long long tot;

int prime[11]={0,2,3,5,7,11,13,17,19,23,29};

void dfs(int now,long long sum,long long num)
{
    if(now==11) return;
    if(sum>tot || sum==tot && num<ans)
    {
        ans=num;
        tot=sum;
    }
    int cnt=0;
    while(num<=n)
    {
        dfs(now+1,sum*(cnt+1),num);
        num*=prime[now];
        cnt++;
    }
}

int main()
{
    scanf("%d",&n);
    dfs(1,1,1);
    printf("%d",ans);
    return 0;
}