hdu 1250(大整数)

最新推荐文章于 2025-09-12 18:08:49 发布

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最新推荐文章于 2025-09-12 18:08:49 发布

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文章标签： java

原文链接：http://www.cnblogs.com/liyinggang/p/5572092.html

本文介绍了一个特殊的四阶斐波那契数列的实现方法，使用Java编程语言并通过BigInteger类来处理可能产生的大数值问题。该程序能够接受用户输入的整数，并输出对应的数列值。

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[7200];
        b[1]=b[2]=b[3]=b[4]= BigInteger.valueOf(1);
        int len = 0;
        for(int i=5;i<7200;i++){
            b[i] = b[i-1].add(b[i-2]).add(b[i-3]).add(b[i-4]);
        }
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            System.out.println(b[n]);
        }
    }
}