HDOJ-1250 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:

 

 1 import java.util.*;

 2 import java.math.*;

 3 public class Main

 4 {

 5     public static void main(String []args)

 6     {

 7         int n,i;        

 8         Scanner cin=new Scanner(System.in);

 9         while(cin.hasNext())

10         {

11             n=cin.nextInt();

12             BigInteger a=BigInteger.valueOf(1);

13               BigInteger b=BigInteger.valueOf(1);

14             BigInteger c=BigInteger.valueOf(1);

15             BigInteger d=BigInteger.valueOf(1);

16             BigInteger e=BigInteger.valueOf(1);

17             for(i=5;i<=n;i++)

18             {

19                 e=a.add(b.add(c.add(d)));

20                 a=b;

21                 b=c;

22                  c=d;

23                 d=e;         

24             }

25             System.out.println(e);    

26         }

27     }

28 }