poj 2506-计算方格摆放的方法数

D - Tiling

Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

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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

题目意思明确了，由于是大数，用java写了。。

java里面注意一点，如果你要运算到第250个数，开数组必须要大于250，也就是从251开始

import java.util.*;
import java.io.BufferedInputStream;
import java.math.*;

public class Main {
	public static void main(String[] args) {

		Scanner cin = new Scanner((System.in));
		BigInteger[] f = new BigInteger[255];
		f[0] = f[1] = BigInteger.ONE;
		for (int i = 2; i <= 254; i++) {
			f[i] = f[i - 1].add(f[i - 2].multiply(BigInteger.valueOf(2)));
		}
		int n;
		while (cin.hasNext()) {
			n = cin.nextInt();
			System.out.println(f[n]);
		}
	}

}