HDU 1709 The Balance

题解：因为天平两边都可以放砝码，所以需要再建一个负的砝码值，然后用母函数即可……

#include <cstdio>
#include <iostream>  
using namespace std;   
int c1[10005],c2[10005],n,sum,res,weight[105];  
int main(){  
    while(scanf("%d",&n)!=EOF){  
        res=sum=0;  
        for(int i=0;i<n;i++){  
            scanf("%d",&weight[i]);   
            sum+=weight[i];  
            weight[n+i]=-weight[i];  
        }  
        memset(c1,0,sizeof(c1)); memset(c2,0,sizeof(c2));  
        for(int i=0;i<=weight[0];i+=weight[0])c1[i]=1;  
        for(int i=1;i<2*n;i++){  
            for(int j=0;j<10005;j++){  
                if(i<=n-1){  
                    for(int k=0;k<=weight[i];k+=weight[i])c2[j+k]+=c1[j];  
                }else{  
                    for(int k=weight[i];k<=0;k+=-weight[i]){  
                        if(j+k>=0)c2[j+k]+=c1[j];  
                    }  
                }  
            }for(int j=0;j<10005;j++)c1[j]=c2[j],c2[j]=0;  
        }for(int i=0;i<=sum;i++)if(c1[i]==0)res++;  
        bool flag=false;  
        printf("%d
",res);  
        if(res!=0){  
            for(int i=0;i<=sum;i++){  
                if(c1[i]==0&&flag==false){  
                    printf("%d",i);  
                    flag=true;  
                }  
                else if(c1[i]==0&&flag)printf(" %d",i);  
            }printf("
");  
        }  
    }return 0;  
}