HDU 1316 How Many Fibs?（java，简单题，大数）

import java.io.*;
import java.util.*;
import java.math.*;

public class Main {

    /**
     * @xqq
     */
    public int an(BigInteger a, BigInteger b, BigInteger sa, BigInteger sb) {
        int ans = 0;
        if(a.compareTo(sa) >= 0 && a.compareTo(sb) ) {
            ans++;
        }
        if(b.compareTo(sa) >= 0 && b.compareTo(sb) ) {
            ans++;
        }
        for(;;) {
            BigInteger c = a.add(b);
            a = b;
            b = c;
            if(b.compareTo(sa) >= 0 && b.compareTo(sb) ) {
                ans++;
            }
            if(b.compareTo(sb) > 0) {
                return ans;
            }
        }
        
    }
    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();
        BigInteger a = BigInteger.valueOf(1);
        BigInteger b = BigInteger.valueOf(2);
        BigInteger sa;
        BigInteger sb;
        BigInteger zero = BigInteger.ZERO;
        
        while(cin.hasNext()) {
            sa = cin.nextBigInteger();
            sb = cin.nextBigInteger();
            if(sa.compareTo(zero) == 0 && sb.compareTo(zero) == 0) {
                break;
            }
            System.out.println(e.an(a, b, sa, sb));
        }
        
        cin.close();  //关闭输入文件
    }
}