poj2506

高精度递推，用java

View Code

   
     

    
      import
    
       java.util.
    
      *
    
      ;

    
      import
    
       java.io.
    
      *
    
      ;

    
      import
    
       java.math.
    
      *
    
      ;


    
      public
    
       
    
      class
    
       Main {
 
    
      static
    
       
    
      public
    
       
    
      void
    
       main (String[] args)
    
      throws
    
       FileNotFoundException
 {
 Scanner cin 
    
      =
    
       
    
      new
    
       Scanner(
    
      new
    
       BufferedInputStream(System.in));
 
    
      //
    
      Scanner cin = new Scanner(new FileInputStream("t.txt"));
    
      

    
       BigInteger[] f 
    
      =
    
       
    
      new
    
       BigInteger[
    
      260
    
      ];
 f[
    
      0
    
      ] 
    
      =
    
       BigInteger.valueOf(
    
      1
    
      );
 f[
    
      1
    
      ] 
    
      =
    
       BigInteger.valueOf(
    
      1
    
      );
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      2
    
      ; i 
    
      <=
    
       
    
      250
    
       ; i
    
      ++
    
      )
 f[i] 
    
      =
    
       f[i 
    
      -
    
       
    
      1
    
      ].add(f[i 
    
      -
    
       
    
      2
    
      ].multiply(BigInteger.valueOf(
    
      2
    
      )));
 
    
      while
    
       (cin.hasNext())
 {
 
    
      int
    
       a 
    
      =
    
       cin.nextInt();
 System.out.println(f[a]);
 }
 }
}