HDU1293+Java+大整数
找规律题。
只要分析到4步的时候差不多规律就出来了。
其次就是大整数!!!!!!!!!
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 import java.util.*; 2 import java.math.*; 3 import java.text.*; 4 import java.io.* ; 5 6 public class Main{ 7 public static void main( String args[] ){ 8 Scanner cin = new Scanner(new BufferedInputStream(System.in)); 9 BigInteger ai[] = new BigInteger[1005]; 10 BigInteger bi[] = new BigInteger[1005]; 11 BigInteger ans[] = new BigInteger[1005]; 12 ai[ 2 ] = BigInteger.valueOf( 2 ); 13 bi[ 2 ] = BigInteger.valueOf( 1 ); 14 for( int i=3;i<1005;i++ ){ 15 bi[ i ] = ai[ i-1 ].add( bi[ i-1 ] ); 16 ai[ i ] = bi[ i-1 ].add( bi[ i ] ); 17 } 18 ans[ 1 ] = BigInteger.valueOf( 3 ); 19 for( int i=2;i<1005;i++ ){ 20 ans[ i ] = ai[ i ].multiply( BigInteger.valueOf(2) ).add( bi[i].multiply(BigInteger.valueOf(3) ) ); 21 } 22 while( cin.hasNext() ){ 23 int n; 24 n = cin.nextInt(); 25 System.out.println( ans[n] ); 26 } 27 } 28 }
keep moving...