装载问题

1、算法设计：
回溯法，用子集树表示其解空间；

template   
class Loading  
{  
    public:  
        void Backtrack(int i);  
        int n,       
            *x,         
            *bestx;     
            Type *w,  
            c,         
            cw,         
            bestw,     
            r;          
};  
template   
void  Loading ::Backtrack (int i);  
  
template  
Type MaxLoading(Type w[], Type c, int n, int bestx[]);  

2、上界函数：

template   
void  Loading ::Backtrack (int i)
{  
    if (i > n)
    {    
        if (cw>bestw)  
        {  
            for(int j=1;j<=n;j++)   
            {  
                bestx[j]=x[j];
                bestw=cw;   
            }  
        }   
        return;  
    }  
  
    r-=w[i];   
    if (cw + w[i] <= c) 
    {   
        x[i] = 1;  
        cw += w[i];  
        Backtrack(i+1);  
        cw-=w[i];      
    }  
  
    if (cw + r > bestw)  
    {  
        x[i] = 0;  
        Backtrack(i + 1);    
    }  
    r+=w[i];   
}  
  
template  
Type MaxLoading(Type w[], Type c, int n, int bestx[])
{  
    LoadingX;  
    X.x=new int[n+1];  
    X.w=w;  
    X.c=c;  
    X.n=n;  
    X.bestx=bestx;  
    X.bestw=0;  
    X.cw=0;  
    X.r=0;  
    for (int i=1;i<=n;i++)  
    {  
        X.r+=w[i];  
    }   
    X.Backtrack(1);  
    delete []X.x;  
    return X.bestw;  
}