HDU 1250(JAVA版)

Hat's Fibonacci

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

Total Submission(s): 7854    Accepted Submission(s): 2551


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

public class Main {
public static void main(String[] args) {
Scanner cin=new Scanner(new BufferedInputStream(System.in));
int n;
BigInteger []a;
while(cin.hasNext())
{
n=cin.nextInt();
if(n<4)
n=4;
a=new BigInteger [n+1];
a[1]=BigInteger.ONE;
a[2]=BigInteger.ONE;
a[3]=BigInteger.ONE;
a[4]=BigInteger.ONE;
for(int i=5;i<=n;i++)
{
a[i]=a[i-1].add(a[i-2]).add(a[i-3]).add(a[i-4]);
}
System.out.println(a
.toString());
}
}
}