zoj Fibonacci Numbers ( java , 简单 ，大数)

题目

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

import java.io.*;

import java.util.*;

import java.math.*;

public class Main {
/**

     * @xqq

     */

    public BigInteger an(int n) {

        BigInteger c;

        BigInteger a = BigInteger.valueOf(1);

        BigInteger b = BigInteger.valueOf(1);
for(int i = 1; i < n; i++) {

            c = a.add(b);

            a = b;

            b = c;

        }

        return a;

    }

    public static void main(String[] args)    throws Exception {

        // 定义并打开输入文件

        Scanner cin = new Scanner(System.in);
Main e = new Main();

        int n;
while(cin.hasNext()) {

            n = cin.nextInt();

            System.out.println(e.an(n));

        }
cin.close();  //关闭输入文件

    }

}

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