一般背包问题 贪心法

#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;

struct goodinfo
{
   float p; //物品效益
   float v; //物品价值
   float w; //物品重量
   float X; //物品该放的数量
   int flag; //物品编号
}; //物品信息结构体

void Insertionsort(goodinfo goods[],int n)
{
   int j,i;
   for(j=2;j<=n;j++)
   {
      goods[0]=goods[j];
      i=j-1;
      while (goods[0].p>goods[i].p)
      {
         goods[i+1]=goods[i];
         i--;
      }
      goods[i+1]=goods[0];
   }
}  //按物品效益，重量比值做升序排列

void bag(goodinfo goods[],float M,int n)
{
     float cu;
     int i,j;
     for(i=1;i<=n;i++)  goods[i].X=0;
     cu=M;  //背包剩余容量
     for(i=1;i<n;i++)
     {
         if(goods[i].w>cu)//当该物品重量大与剩余容量跳出
              break;
        goods[i].X=1;
        cu=cu-goods[i].w;//确定背包新的剩余容量
     }
     if(i<=n)
     goods[i].X=cu/goods[i].w;//该物品所要放的量
    //按物品编号做降序排列
    for(j=2;j<=n;j++)
    {
       goods[0]=goods[j];
       i=j-1;
       while(goods[0].flag<goods[i].flag)
       {
          goods[i+1]=goods[i];
          i--;
       }
       goods[i+1]=goods[0];
    }
    double sum=0.0;
    cout<<"最优解为:(";
    for(i=1;i<=n;i++)
    {
       if(i==1)
       cout<<goods[i].X;
       else
        cout<<","<<goods[i].X;
       if(goods[i].X!=0)
        sum+=goods[i].X*goods[i].v;
    }
    cout<<")"<<endl;
    cout<<"最优解值为:"<<sum<<endl;
}
int main()
{
     cout<<"|---------运用贪心法解背包问题---------|"<<endl;
     cout<<"|--------------------------------------|"<<endl;
     int i,n;
     float M;
     goodinfo *goods;     //定义一个指针
     cout<<"请输入物品的总数量：";
     while(cin>>n)
     {
        goods=new struct goodinfo [n+1];
        cout<<"请输入背包的最大容量：";
        cin>>M;
        cout<<endl;
        cout<<"请输入"<<n<<"个背包的重量(空格分割):"<<endl;
        for(i=1;i<=n;i++)
        {
            goods[i].flag=i;
            cin>>goods[i].w;
        }
        cout<<"请输入"<<n<<"个背包的价值(空格分割):"<<endl;
        for(i=1;i<=n;i++)
        {
            cin>>goods[i].v;
            goods[i].p=goods[i].v/goods[i].w;   //得出物品的效益，重量比
        }
        Insertionsort(goods,n);
        bag(goods,M,n);
   }
   return 0;
}

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