URAL1054[Hanoi tower]

就是倒着放回去，一直放到初始状态。

CODE:

/*

PROGRAM: $PROGRAM

AUTHOR: Su Jiao

DATE: 2010-3-27

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

{

      int N;

      vector<int> pos;

      static void swap(int& a,int& b)

      {

             static int s;

             s=a;

             a=b;

             b=s;

      }

      public:

      Application()

      {

                   cin>>N;

                   pos.resize(N);

                   for (int i=0;i<N;i++) cin>>pos[i];

      }

      int run()

      {

          int step=0;

          bool can=true;

          int a=1,b=2,c=3;

          for (int i=N-1;i>=0;i–)

          {

              if (pos[i]==a) 

                 swap(b,c);

              else if (pos[i]==b)

                   swap(a,c),step+=1<<i;

              else can=false;

          }

          if (can) cout<<step<<endl;

          else cout<<-1<<endl;

          return 0;

      }

};

 

int main()

{

    Application app;

    return app.run();

}