Cod sursă (job #755945)

#include <fstream>

using namespace std;

ifstream cin ( "2sah.in" ) ;
ofstream cout ( "2sah.out" ) ;

int mat [ 2000002 ] [ 2 ] ;

int main()
{
    int cerinta , n , k ;
    cin >> cerinta ;
    cin >> n >> k ;
    mat [ n ] [ 0 ] = 1 ;

    int sum = 0 ;

    for ( int i = 0 ; i < k - 1 ; i ++ ) {
         for ( int j = n - i - 1 ; j <= n + i + 1 ; j ++ ) {
            mat [ j ] [ ( i + 1 ) % 2 ] = mat [ j - 1 ] [ i % 2 ] + mat [ j ] [ i % 2 ] + mat [ j + 1 ] [ i % 2 ] ;
            mat [ j ] [ ( i + 1 ) % 2 ] = mat [ j ] [ ( i + 1 )% 2 ] % 100003 ;
        }

         if ( i == k - 2 ) {
            for ( int j = n - i - 1 ; j <= n + i + 1 ; j ++ ) {
               sum = sum + mat [ j ] [ ( i + 1 ) % 2 ] ;
               sum = sum  % 100003 ;
            }
         }
    }
    cout << sum ;
    return 0;
}