hdu 1250 Hat's Fibonacci

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Hat's Fibonacci

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

Total Submission(s): 5590    Accepted Submission(s): 1866


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
4203968145672990846840663646Note:No generated Fibonacci number in excess of 2005 digits will be in the test data, ie. F(20) = 66526 has 5 digits.
 

import java.math.BigInteger;import java.util.Scanner;public class Main{/* * n<7040 */public static void main(String[] args) {Scanner input=new Scanner(System.in);//F f[]=new F[10000000];7040BigInteger f[]=new BigInteger[8];while(input.hasNext()){f[1]=BigInteger.valueOf(1);f[2]=BigInteger.valueOf(1);f[3]=BigInteger.valueOf(1);f[4]=BigInteger.valueOf(1);int n=input.nextInt();if(n<=4){System.out.println(f[n]);}else {for(int i=5;i<=n;i++){f[5]=f[1].add(f[2].add(f[3].add(f[4])));f[1]=f[2];f[2]=f[3];f[3]=f[4];f[4]=f[5];}System.out.println(f[5].toString());}}}}



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