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位  

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();

}