USACO 1.4 Arithmetic Progressions

USACO 1.4 Arithmetic Progressions

用一个bool数组标记一下，然后暴力....最长3秒多，题目要求5秒以内即可。

#include  < iostream >
#include  < fstream >
#include  < vector >

using   namespace  std;

ifstream fin( " ariprog.in " );
ofstream fout( " ariprog.out " );

#ifdef _DEBUG
#define  out cout
#define  in cin
#else
#define  out fout
#define  in fin
#endif

bool  mark[ 250 * 250 * 2 + 1 ];

void  solve()
{
     int  n,m;
     in >> n >> m;

    memset(mark, 0 , sizeof (mark));

     for ( int  i = 0 ;i <= m; ++ i)
         for ( int  j = i;j <= m; ++ j){
            mark[i * i + j * j]  =   true ;
        }

     int  max  =  m * m * 2 + 1 ;

    vector < int > v;
    v.reserve(max);

     for ( int  i = 0 ;i < max; ++ i)
         if (mark[i])
            v.push_back(i);

     int  size  =  v.size();

     int  max_len  =  (v[size - 1 ] - v[ 0 ]) / (n - 1 );

     bool  find  =   false ;

     for ( int  len = 1 ;len <= max_len;len ++ ){
         for ( int  i = 0 ;i < size; ++ i){
             int  cnt  =  n - 1 ;
             int  t  = v[i];
             while (cnt){
                t += len;
                 if (t > v[size - 1 ])
                     break ;
                 if ( ! mark[t])
                     break ;
                cnt -- ;
            }

             if (cnt == 0 ){
                find  =   true ;
                 out << v[i] << '   ' << len << endl;
            }
        }
    }

     if ( ! find)
         out << " NONE " << endl;
}

int  main( int  argc, char   * argv[])
{
  solve();
   return   0 ;
}