ZOJ 2109 FatMouse' Trade

  
    

   
     /*
   
     
抄书上的程序..
用c语言写的老是WA
  
    
  
    

   
     每次选效益最高的交换

   
     */
   
     
#include 
   
     <
   
     iostream
   
     >
   
     
#include 
   
     <
   
     fstream
   
     >
   
     
#include 
   
     <
   
     vector
   
     >
   
     
#include 
   
     <
   
     algorithm
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;

   
     struct
   
      Mouse
{
 
   
     double
   
      j,f;
 
   
     double
   
      shouyi;
};

   
     bool
   
      comp(
   
     const
   
      Mouse 
   
     &
   
     d1,
   
     const
   
      Mouse 
   
     &
   
     d2){
 
   
     if
   
     (d1.shouyi 
   
     !=
   
      d2.shouyi)
 
   
     return
   
      d2.shouyi 
   
     <
   
      d1.shouyi;
 
   
     return
   
      d2.f 
   
     >
   
      d1.f;
}

   
     int
   
      main(){
 
   
     //
   
     ifstream cin("2109.txt");
   
     

   
      vector
   
     <
   
     Mouse
   
     >
   
      v;
 Mouse mouse;
 
   
     int
   
      m,n,i;
 cout.precision(
   
     3
   
     ); 
   
     //
   
     三位小数
   
     

   
      
   
     double
   
      sum;
 
   
     while
   
     (cin 
   
     >>
   
      m 
   
     >>
   
      n){
 
   
     if
   
     (m 
   
     ==
   
      
   
     -
   
     1
   
      
   
     &&
   
      n 
   
     ==
   
      
   
     -
   
     1
   
     )
 
   
     break
   
     ;
 v.clear();
 sum 
   
     =
   
      
   
     0.0
   
     ;
 
   
     for
   
     (i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      n; 
   
     ++
   
     i){
 cin 
   
     >>
   
      mouse.j 
   
     >>
   
      mouse.f;
 mouse.shouyi 
   
     =
   
      mouse.j 
   
     /
   
      mouse.f;
 v.push_back(mouse);
 }
 sort(v.begin(),v.end(),comp);
 
   
     for
   
     (i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      v.size(); i
   
     ++
   
     ){
 
   
     if
   
     (m 
   
     >=
   
      v[i].f){
 sum 
   
     +=
   
      v[i].j;
 m 
   
     -=
   
      (
   
     int
   
     )v[i].f;
 } 
   
     else
   
      {
 sum 
   
     +=
   
      m 
   
     *
   
      v[i].shouyi;
 
   
     break
   
     ;
 }
 }
 cout 
   
     <<
   
      
   
     fixed
   
      
   
     <<
   
      sum 
   
     <<
   
      endl;
 }
 
   
     return
   
      
   
     0
   
     ;
}