HDU1250 Hat's Fibonacci 【大数】

Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 7616    Accepted Submission(s): 2474

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.
   
   
   
   

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

public class Main{
	public static void main(String[] args){
		Scanner cin = new Scanner(System.in);
		BigInteger a, b, c, d;
		BigInteger[] arr = new BigInteger[10000];
		arr[1] = arr[2] = arr[3] = arr[4] = BigInteger.ONE;
		arr[5] = BigInteger.valueOf(4);
		for(int i = 6; i < 10000; ++i)
			arr[i] = arr[i-1].add(arr[i-2]).add(arr[i-3]).add(arr[i-4]);
		int n;
		while(cin.hasNext()){
			n = cin.nextInt();
			System.out.println(arr[n]);
		}
	}
}