URAL1040[Airline company]

看了题解做的，题解大意是，DFS标记边的时候依次标1到M，这样任何一个点连到的边若超过1条，就必定有两条的标号相差1。所以满足条件（并且一定有解，所以输NO骗分是无用的）。

CODE:

/*

PROGRAM: $PROGRAM

AUTHOR: Su Jiao

DATE: 2010-3-22

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;

#include <set>

using std::set;

#include <map>

using std::map;

using std::pair;

using std::make_pair;

#include <algorithm>

using std::sort;

#include <cassert>

//using std::assert;

 

class Application

{

      static const int NOMARK=-1;

      int N,M;

      vector<pair<pair<int,int>,int> > flight;

      void dfs(int node,int& mark)

      {

           for (int i=0;i<M;i++)

           {

               if (flight[i].second==NOMARK)

               {

                  if (flight[i].first.first==node)

                  {

                     flight[i].second=mark;

                     mark++;

                     dfs(flight[i].first.second,mark);

                  }

                  if (flight[i].first.second==node)

                  {

                     flight[i].second=mark;

                     mark++;

                     dfs(flight[i].first.first,mark);

                  }

               }

           }

      }

      public:

      Application()

      {

                    cin>>N>>M;

                    flight.resize(M);

                    for (int i=0;i<M;i++)

                    {

                        cin>>flight[i].first.first

                           >>flight[i].first.second;

                        flight[i].second=NOMARK;

                    }

      }

      int run()

      {

          int mark=1;

          for (int i=1;i<=N;i++)

              dfs(i,mark);

         

          cout<<“YES”<<endl;

          for (int i=0;i<M;i++)

              cout<<flight[i].second<<char(i+1==M?’\n’:’ ‘);

          return 0;

      }

};

 

int main()

{

    Application app;

    return app.run();

}