3062717_ac_937ms_5368k.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);
		BigInteger t, two = new BigInteger("2");
		int n, p;
		
		while(cin.hasNext())
		{
			n = cin.nextInt();
			t = BigInteger.ONE;
			p = 0;
			if(n%2==0)
			{
				p = 1;
				t = two;
			}
			System.out.println(two.pow(n-1).subtract(t).divide(BigInteger.valueOf(3)).add(BigInteger.valueOf(p)));
		}
	}
}