greedy 部分背包问题

/*  STL       map应用 
  *  Greedy   部分背包问题 
  *  newplan  开发时间: 08.5 . 13   
*/
/*-------- INCLUDES ----------*/  
#include  < cstdlib >
#include  < iostream >
#include  < map >
#include  < fstream >  
#include  < iomanip >
/*-------- INCLUDES ----------*/  

/*--------- MACROS -----------*/
#define INPUTFILE   " bag.txt "
/*--------- MACROS -----------*/

/*---------- STD -------------*/
using std::ifstream;
using std::cout;
using std::endl;
using std::map;
using std::greater;
using std::ios;
using std::setw;
/*---------- STD -------------*/

/*------- GLOBAL VAL ---------*/
ifstream  Fin;
int  n;
int  W;
int  totalValue;
/*------- GLOBAL VAL ---------*/

/*--------- MAIN -------------*/
int  main( int  argc, char  * argv[])
{  
 
    map < int , int ,greater < int >   >  goods;
    
    Fin.open(INPUTFILE);
 
     int  value;
    
     int  weight;
    
    Fin >> W;
    
    Fin >> n;
    
     int  i;
     for (i = 0 ;i < n;i ++ )
    {
       Fin >> value;
       Fin >> weight;
       goods[value] = weight;
    }

     for (map < int , int > ::iterator it  =  goods.begin();it! = goods.end();it ++ )
    {
     cout << setiosflags(ios:: left ) << " value: " << setw( 4 ) << it -> first
      << "  weight: " << setw( 4 ) << it -> second << endl;
    }
    
     for (map < int , int > ::iterator it  =  goods.begin();it! = goods.end();it ++ )
    {
       if (W - it -> second >= 0 )
      {
         W -= it -> second ;
         totalValue += it -> first * it -> second ;
         cout << " w= " << W << "   " ;
      }
       else  
      {
         totalValue += W * it -> first;
         cout << " totalValue: " << totalValue << endl;
         break;  
      }
      
    }
    
    system( " PAUSE " );
    return EXIT_SUCCESS;
}
/*--------- MAIN -------------*/
BAG.TXT
100   10
3   43
5   22
6    4
4   67
2    3
45  2
4   2
42  24
41  4
34  55