hdu 1250 Hat's Fibonacci(java大数)

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Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 7407    Accepted Submission(s): 2414

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.
  
  

用Java写的Fibonacci 数组。

代码：

import java.math.*;
import java.util.*;
public class Main {

    public static void main(String[] args) {
      // TODO Auto-generated method stub
        Integer n,i,N = 9001;
        BigInteger []f = new BigInteger[N];
        f[1] = f[2] = f[3] = f[4] = BigInteger.valueOf(1);
        for(i = 5; i < N; ++i)
            f[i] = f[i-1].add(f[i-2]).add(f[i-3]).add(f[i-4]);
        
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            n  = cin.nextInt();
            System.out.println(f[n]);
            //System.out.println(f[n].toString().length());
        
        }
        cin.close();
    }

}