Hat's Fibonacci（JAVA大数）

Hat’s Fibonacci
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12003 Accepted Submission(s): 4022

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.

//JAVA大数水过….就是一个递推题 然而数值比较大

import java.math.BigInteger;import java.util.Scanner;public class Main {    public static void main(String[] args) {        int n;        Scanner cin = new Scanner(System.in);        BigInteger []qq = new BigInteger[10001];        qq[1] = qq[2] = qq[3] = qq[4] = BigInteger.ONE;        for(int i = 5;i<=10000;i++)            qq[i] = BigInteger.ZERO;        while (cin.hasNext()) {            BigInteger f1 =BigInteger.ONE;            BigInteger f2 =BigInteger.ONE;            BigInteger f3 =BigInteger.ONE;            BigInteger f4 =BigInteger.ONE;            n = cin.nextInt();            BigInteger sum = BigInteger.ZERO ;            if(qq[n]!=BigInteger.ZERO)            {                System.out.println(qq[n]);            }            else            {                for(int i = 5;i<=n;i++)                {                    sum = f1.add(f2).add(f3).add(f4);                    f1 = f2;                    f2 = f3;                    f3 = f4;                    f4 = sum;                }                System.out.println(sum);                qq[n] = sum;            }        }    }}