hdu 1250(大整数)

Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 10430    Accepted Submission(s): 3447

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.

 

2005位的数大概在7100左右

import java.math.BigInteger;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        BigInteger [] b = new BigInteger[];
        b[]=b[]=b[]=b[]= BigInteger.valueOf();
        int len = ;
        for(int i=;i<;i++){
            b[i] = b[i-].add(b[i-]).add(b[i-]).add(b[i-]);
        }
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            System.out.println(b[n]);
        }
    }
}