3019178_ac_26218ms_32040k.java

北大大牛代码 1240道题的原代码 超级权威

import java.util.*;
import java.math.*;

public class Main 
{
	
	public static void main(String[] args) 
	{
		Scanner cin = new Scanner (System.in);
		int i, n;
		BigInteger a[] = new BigInteger [10001];
		BigInteger two = new BigInteger ("2");
		
		a[1] = a[0] = BigInteger.ONE;
		a[2] = BigInteger.valueOf(3);
		for(i = 3; i <= 10000; i++)
		{
			a[i] = two.multiply(a[i-1].add(a[i-2])).subtract(a[i-3]);
		}
		for(i = 0; i <= 10000; i++)
		{
			a[i] = a[i].multiply(a[i]);
		}
		BigInteger four = two.add(two);
		while(cin.hasNext())
		{
			n = cin.nextInt();
			String tmp = four.multiply(a[n]).toString();
			int len = tmp.length();
			for(i = 0; i < (len%3==0?3:len%3); i++)
			{
				System.out.print(tmp.charAt(i));
			}
			int mark;
			mark = 0;
			for(; i < len; i++)
			{
				if(mark==0)
				{
					System.out.print(',');
				}
				System.out.print(tmp.charAt(i));
				mark++;
				if(mark==3)
				{
					mark = 0;
				}
			}
			System.out.println();
		}
	}
}