URAL1020[Rope]

水题,不过C++的要自己背一下PI的值,貌似URAL不能用<cmath>中的M_PI。


CODE:


/*


PROGRAM: $PROGRAM


AUTHOR: Su Jiao


DATE: 2010-3-18


DESCRIPTION:


$DESCRIPTION


*/


#include <iostream>


using std::cin;


using std::cout;


#include <fstream>


using std::ifstream;


using std::ofstream;


#include <sstream>


using std::stringstream;


using std::endl;


#include <vector>


using std::vector;


#include <string>


using std::string;


#include <stack>


using std::stack;


#include <queue>


using std::queue;


using std::deque;


#include <map>


using std::map;


using std::pair;


using std::make_pair;


#include <algorithm>


using std::sort;


#include <cassert>


//using std::assert;


#include <cmath>


//using std::M_PI;


#define M_PI (3.141592653589793238462643383279f) //哈哈 我会背PI小数点后30  


using std::sqrt;


#include <iomanip>


 


class Application


{


      typedef vector<pair<double,double> > vpdd;


      typedef vector<pair<double,double> >::iterator vpddi;


      int N;


      double R;


      vpdd point;


      public:


      Application()


      {


                    cin>>N>>R;


                    point.resize(N);


                    for (vpddi it=point.begin();


                         it!=point.end();


                         it++)


                        cin>>it->first>>it->second;


      }


      int run()


      {


          double answer=M_PI*R*2.0f;


          for (vpddi it=point.begin();;)


          {


               vpddi to=it++;


               if (it==point.end()) it=point.begin();


               answer+=sqrt((to->first-it->first)


                             *(to->first-it->first)


                            +(to->second-it->second)


                             *(to->second-it->second));


               if (it==point.begin()) break;


          }


          cout<<std::setiosflags(std::ios::fixed)


              <<std::setprecision(2)


              <<answer<<endl;


          return 0;


      }


};


 


int main()


{


    Application app;


    return app.run();


}


 


 

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