poj-2506-填瓷砖

Tiling

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 10753		Accepted: 4996

Description

In how many ways can you tile a 2xn rectangle by 2x1 or 2x2 tiles? 
Here is a sample tiling of a 2x17 rectangle. 

Input

Input is a sequence of lines, each line containing an integer number 0 <= n <= 250.

Output

For each line of input, output one integer number in a separate line giving the number of possible tilings of a 2xn rectangle. 

Sample Input

2
8
12
100
200

Sample Output

3
171
2731
845100400152152934331135470251

1071292029505993517027974728227441735014801995855195223534251

import java.math.BigInteger;
import java.util.Scanner;
public class Main {
    private static Scanner in;
    public static void main(String[] args) {
    	// TODO Auto-generated method stub
    	int n;
        BigInteger a[]=new BigInteger[300];//新建对象     
        a[0]=BigInteger.valueOf(1);//2*0的时候，只要一种情况
        a[1]=BigInteger.valueOf(1);//2*1的时候，只有一种情况
        a[2]=BigInteger.valueOf(3);//2*2的时候，有三种情况（其中一种与上一个重复）
        for(int i=3;i<300;i++)
            a[i]=a[i-1].add(a[i-2].multiply(BigInteger.valueOf(2)));//递推得公式：a[i]=a[i-1]+a[i-2]*2
        Scanner in=new Scanner(System.in);//扫描从控制台输入的字符
        while(in.hasNext())//等价于!=EOF
        {
        	n=in.nextInt();//读入一个int型的数
           // System.out.println(a[in.nextInt()]);//从输入流读取下一个整数
        	System.out.println(a[n]);
        }
    }
}