HDU 1250 Hat's Fibonacci (Java大数,类似Fib数,有个坑!!)

Hat's Fibonacci

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 10352    Accepted Submission(s): 3412

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.
   
   
   
   

 

Author

戴帽子的

原题链接:http://acm.hdu.edu.cn/showproblem.php?pid=1250

坑,题目下面的

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

意思不是测试的数据结果不会超过2005位??!!我开了3000了WA,看别人的代码开了10005,就A了,看来我的英语真的有待提高!!????

AC代码:

import java.math.BigDecimal;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        BigDecimal a[] = new BigDecimal [10005];
        //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)
        a[1]=a[2]=a[3]=a[4]=new BigDecimal(1);
        for (int i = 5; i <10005 ; i++) {
            a[i] = a[i-1].add(a[i-2]).add(a[i-3]).add(a[i-4]);
        }
        while(sc.hasNext()){
            int n = sc.nextInt();
            System.out.println(a[n]);
        }
    }
    
}