HDOJ1250 大数斐波那契问题[大数加法]

Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3554    Accepted Submission(s): 1208

Problem Description

A Fibonacci sequence is calculated by adding the previous two members the sequence, with the first two members being both 1.
F(1) = 1, F(2) = 1, F(3) = 1,F(4) = 1, F(n>4) = F(n - 1) + F(n-2) + F(n-3) + F(n-4)
Your task is to take a number as input, and print that Fibonacci number.

 

Input

Each line will contain an integers. Process to end of file.

 

Output

For each case, output the result in a line.

 

Sample Input

100

 

Sample Output

4203968145672990846840663646 Note: No generated Fibonacci number in excess of 2005 digits will be in the test data, ie. F(20) = 66526 has 5 digits.

 

Author

戴帽子的

 

Recommend

Ignatius.L

 

 

code:

 

import java.util.*;
import java.math.*;
public class Main
{
    public static void main(String []args)
    {
        int n,i;        
        Scanner cin=new Scanner(System.in);
        while(cin.hasNext())
        {
            n=cin.nextInt();
            BigInteger a=BigInteger.valueOf(1);
              BigInteger b=BigInteger.valueOf(1);
            BigInteger c=BigInteger.valueOf(1);
            BigInteger d=BigInteger.valueOf(1);
            BigInteger e=BigInteger.valueOf(1);
            for(i=5;i<=n;i++)
            {
                e=a.add(b.add(c.add(d)));
                a=b;
                b=c;
                 c=d;
                d=e;         
            }
            System.out.println(e);    
        }
    }
}