Arbitrage--POJ 2240

1、题目类型：图论、最短路径、Floyd算法。

2、解题思路：Floyd算法的简单应用；STL中map的简单应用。

3、注意事项：避免map报警告，文件开始调用#pragma warning(disable:4786)。

4、实现方法:

  
    

   
     
   
     #pragma
   
      warning(disable:4786)
   
     
#include
   
     <
   
     iostream
   
     >
   
     
#include
   
     <
   
     map
   
     >
   
     
#include
   
     <
   
     string
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;


   
     double
   
      Map[
   
     30
   
     ][
   
     30
   
     ];

   
     int
   
      n;
map
   
     <
   
     string
   
     ,
   
     int
   
     >
   
     node;


   
     void
   
      Floyed()
{
 
   
     int
   
      i,j,k;
 
   
     for
   
     (k
   
     =
   
     0
   
     ;k
   
     <
   
     n;k
   
     ++
   
     )
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     n;i
   
     ++
   
     )
 
   
     for
   
     (j
   
     =
   
     0
   
     ;j
   
     <
   
     n;j
   
     ++
   
     )
 {
 
   
     if
   
     ( Map[i][j]
   
     <
   
     Map[i][k]
   
     *
   
     Map[k][j] )
 Map[i][j]
   
     =
   
     Map[i][k]
   
     *
   
     Map[k][j];
 }
}


   
     int
   
      main()
{
 
   
     int
   
      i,j
   
     =
   
     0
   
     ,m;
 
   
     double
   
      k;
 
   
     bool
   
      flag;
 
   
     string
   
      tmp,tmp1;
 
   
     while
   
     (cin
   
     >>
   
     n
   
     &&
   
     n)
 {
 j
   
     ++
   
     ;
 flag
   
     =
   
     0
   
     ;
 memset(Map,
   
     0
   
     ,
   
     sizeof
   
     (Map));
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     n;i
   
     ++
   
     )
 {
 Map[i][i]
   
     =
   
     1.0
   
     ;
 cin
   
     >>
   
     tmp;
 node[tmp]
   
     =
   
     i;
 }
 cin
   
     >>
   
     m;
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     m;i
   
     ++
   
     )
 {
 cin
   
     >>
   
     tmp
   
     >>
   
     k
   
     >>
   
     tmp1;
 Map[node[tmp]][node[tmp1]]
   
     =
   
     k;
 }
 Floyed(); 
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     n;i
   
     ++
   
     )
 {
 
   
     if
   
     (Map[i][i]
   
     >
   
     1.0
   
     )
 {
 flag
   
     =
   
     1
   
     ;
 
   
     break
   
     ;
 }
 }
 cout
   
     <<
   
     "
   
     Case 
   
     "
   
     <<
   
     j
   
     <<
   
     "
   
     : 
   
     "
   
     ;
 
   
     if
   
     (flag)
 cout
   
     <<
   
     "
   
     Yes
   
     "
   
     <<
   
     endl;
 
   
     else
   
     
 cout
   
     <<
   
     "
   
     No
   
     "
   
     <<
   
     endl;
 }
 
   
     return
   
      
   
     0
   
     ;
}