#include "iostream"
using namespace std;
struct goodinfo
{
 float p; //物品效益
 float w; //物品重量
 float X; //物品該放的數(shù)量
 int flag; //物品編號(hào)
};//物品信息結(jié)構(gòu)體
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)//當(dāng)該物品重量大與剩余容量跳出
   break;
  goods[i].X=1;
  cu=cu-goods[i].w;//確定背包新的剩余容量
 }
 if(i<=n)
  goods[i].X=cu/goods[i].w;//該物品所要放的量
 //按物品編號(hào)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];
 }
 cout<<"最優(yōu)解為:"<<endl;
 for(i=1;i<=n;i++)
 {
  cout<<"第"<<i<<"件物品要放:";
  cout<<goods[i].X<<endl;
 }
}
int main(void)
{
 cout<<"|--------運(yùn)用貪心法解背包問題---------|"<<endl;
 cout<<"|-------------------------------------|"<<endl;
 int i,j,n;
 float M;
 goodinfo *goods;     //定義一個(gè)指針
 cout<<"press <1> to run the program"<<endl;
 cout<<"press <0> to exit"<<endl;
 cin>>j;
 while(j)
 {
  cout<<"請輸入物品的總數(shù)量：";
  cin>>n;
  goods=new struct goodinfo [n+1];
  cout<<"請輸入背包的最大容量：";
  cin>>M;
  cout<<endl;
  for(i=1;i<=n;i++)
  {
   goods[i].flag=i;
   cout<<"請輸入第"<<i<<"件物品的重量:";
   cin>>goods[i].w;
   cout<<"請輸入第"<<i<<"件物品的效益:";
   cin>>goods[i].p;
   goods[i].p=goods[i].p/goods[i].w;   //得出物品的效益，重量比
   cout<<endl;
  }
  Insertionsort(goods,n);
  bag(goods,M,n);
  cout<<"press <1> to run agian"<<endl;
  cout<<"press <0> to exit"<<endl;
  cin>>j;
 }
 system("pause");
 return 0;
}