URAL1005[Stone pile]

很水的背包，方程f[i]=f[i] or f[i-W[k]]。

CODE:

/*

PROGRAM: $PROGRAM

AUTHOR: Su Jiao

DATE: 2010-3-10

DESCRIPTION:

$DESCRIPTION

*/

#include <iostream>

using std::cin;

using std::cout;

using std::endl;

#include <vector>

using std::vector;

#include <string>

using std::string;

#include <stack>

using std::stack;

#include <queue>

using std::queue;

#include <map>

using std::map;

using std::pair;

using std::make_pair;

#include <cassert>

//using std::assert;

 

class Application

{

      static const int oo=~(1<<31);

      int N;

      vector<int> W;

      int total;

      public:

      Application()

                    :total(0)

      {

                    cin>>N;

                    W.resize(N);

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

                    {

                        cin>>W[i];

                        total+=W[i];

                    }

      }

      int run()

      {

          vector<bool> f(total+1,false);

          f[0]=true;

          for (int k=0;k<N;k++)

              for (int i=total;i>=W[k];i–)

                  f[i]=f[i] or f[i-W[k]];

         

          int answer=oo;

          for (int i=(total+1)/2;i<=total;i++)

          {

              if (f[i])

              {

                 answer=i*2-total;

                 break;

              }

          }

          cout<<answer<<endl;

          return 0;

      }

};

 

int main()

{

    Application app;

    return app.run();

}