java高精度数组

 1 import java.util.*;
 2 import java.math.*;
 3 
 4 public class Main
 5 {
 6     public static void main(String[] args) 
 7     {
 8         Scanner cin = new Scanner(System.in);
 9         BigInteger a[] = new BigInteger[101];
10         a[1] = BigInteger.ONE;
11         a[2] = BigInteger.valueOf(3);
12         BigInteger Three = BigInteger.valueOf(3);
13         for(int i=3; i<=100; i++)
14             a[i] = Three.multiply(a[i-1]).subtract(a[i-2]);
15         while(cin.hasNext())
16         {
17             int n = cin.nextInt();
18             System.out.println(a[n]);
19         }
20     }
21 }