zcmu 1041

1041: 二哥的困惑 Ⅳ

Description

 

A Fibonacci sequence is calculated by adding the previous two members of the sequence, with the first two members being both 1.

f(1) = 1, f(2) = 1, f(n > 2) = f(n - 1) + f(n - 2)

Your task is to take a number as input, and print that Fibonacci number.

Input

Input contains several cases, every case contains a positive integer number N.

Output

print the Nth Fibonacci number.

Sample Input

100

Sample Output

354224848179261915075

 

思路：数值太大，直接用Java大数处理。

代码如下：

import java.math.BigInteger;
import java.util.Scanner;
public class Main{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        int n;
        BigInteger a[] = new BigInteger[1005];
        while(in.hasNext()) {
            n = in.nextInt();
            a[1] = BigInteger.valueOf(1);
            a[2] = BigInteger.valueOf(1);
            for(int i = 3;i <= n;i++) {
                a[i] = a[i-1].add(a[i-2]);
            }
            System.out.println(a[n]);
        }
    }
}