HDU3092(改编完全背包问题)

解题思路：详见https://blog.youkuaiyun.com/acm_cxq/article/details/51626668

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define N 3008
#define ll long long
using namespace std;
int p[N],r[N],t;
double dp[3009];
ll n,m,ans[3009];
void prime()
{
	t=0;
	for(int i=2;i<N;i++)
	{
		if(!p[i])
		{
			r[t++]=i;
			for(int j=i+i;j<N;j+=i)
			p[j]=1;
		}
	}
}
void solve()
{
	memset(dp,0,sizeof(dp));
	double a;
	for(int i=0;i<t;i++)
	{
		a=log(r[i]*1.0);
		for(int j=n;j>=r[i];j--)
		{
			for(int k=r[i],q=1;k<=j;k*=r[i],q++)
			{
				if(dp[j-k]+q*a>dp[j])
				{
					dp[j]=dp[j-k]+q*a;
					ans[j]=(ans[j-k]*k)%m;
				}
			}
		}
	}
	printf("%lld\n",ans[n]);
}
int main()
{
	prime();
	//freopen("t.txt","r",stdin);
	while(scanf("%d%d",&n,&m)!=EOF)
	{
 		for(int i=0;i<=n;i++)
        {
            dp[i]=0;
            ans[i]=1;
        }
		solve();
	}
	return 0;
}