hdu 1709 The Balance

母函数的特殊情况，左右两边都可以放，如样例1，2，9

母函数为(1+x+1/x)*(1+x^2+1/x^2)*(1+x^9+1/x^9)

化简为(1+x+x^2)*(1+x^2+x^4)*(1+x^9+x^18)/(x*x^2*x^9)

这样就好计算了，看代码：

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<vector>
#include<stdlib.h>
using namespace std;
__int64 a[30001],b[30001],an[10001];
int main()
{
    int i,j,k,n,sum,num;
    while (cin>>n&&n){
        sum=0;num=0;
        for(i=0;i<n;i++){
            cin>>an[i];
            sum+=an[i];
        }
        memset(a,0,sizeof(a));
        memset(b,0,sizeof(b));
        for(i=0;i<=2*an[0];i+=an[0])
            a[i]=1;
        for(i=1;i<n;i++){
            for(j=0;j<=sum;j++)
                for(k=0;k<=sum&&k<=2*an[i];k+=an[i]){
                    b[j+k]+=a[j];
                }
            for(j=0;j<=sum;j++){
                a[j]=b[j];
                b[j]=0;
            }
        }
        for(i=sum,j=0;i>=0;i--)
            if(a[i]==0){
                num++;
                an[j++]=sum-i;
            }
        if(num==0)
        {
            cout<<num<<endl;
            continue;
        }
        cout<<num<<endl<<an[0];
        for(i=1;i<num;i++)
            cout<<' '<<an[i];
        cout<<endl;
    }
    return 0;
}