UVa 537 Artificial Intelligence?

UVa 537 Artificial Intelligence?

从string中寻找"P="、"U="、"I="，然后记录P、U、I的值，使用istringstream比较方便。
以下是我的代码：

#include < iostream >
#include < sstream >
#include < string >
#include < cstdio >
using   namespace  std;

int  main()
{
     /*
    freopen("data.in","r",stdin);
    freopen("data.out","w",stdout);
    // */

     int  T;
    cin >> T;getchar();
     for ( int  case_num = 1 ;case_num <= T;case_num ++ )
    {
         string  line;
        getline(cin,line);
         double  P( - 1.0 ),U( - 1.0 ),I( - 1.0 );
        istringstream sin(line);
         char  ch;
         while (sin >> ch)
        {
             if (ch == ' P ' )
            {
                 char  t;
                sin >> t;
                 if (t != ' = ' )
                     continue ;
                sin >> P;
                sin >> t;
                 if (t == ' m ' )
                    P /= 1000 ;
                 else   if (t == ' k ' )
                    P *= 1000 ;
                 else   if (t == ' M ' )
                    P *= 1000000 ;
            }
             else   if (ch == ' U ' )
            {
                 char  t;
                sin >> t;
                 if (t != ' = ' )
                     continue ;
                sin >> U;
                sin >> t;
                 if (t == ' m ' )
                    U /= 1000 ;
                 else   if (t == ' k ' )
                    U *= 1000 ;
                 else   if (t == ' M ' )
                    U *= 1000000 ;
            }
             else   if (ch == ' I ' )
            {
                 char  t;
                sin >> t;
                 if (t != ' = ' )
                     continue ;
                sin >> I;
                sin >> t;
                 if (t == ' m ' )
                    I /= 1000 ;
                 else   if (t == ' k ' )
                    I *= 1000 ;
                 else   if (t == ' M ' )
                    I *= 1000000 ;
            }
        }

        cout << " Problem # " << case_num << endl;
         if (P ==- 1.0 )
            printf( " P=%.2fW\n " ,U * I);
         else   if (U ==- 1.0 )
            printf( " U=%.2fV\n " ,P / I);
         else
            printf( " I=%.2fA\n " ,P / U);
        printf( " \n " );
    }

     return   0 ;
}