POJ 2413 How many Fibs? （java大数）

How many Fibs?

Description

Recall the definition of the Fibonacci numbers:

f1 := 1
f2 := 2
fn := f

_n-1

 + f

_n-2

     (n>=3) 

Given two numbers a and b, calculate how many Fibonacci numbers are in the range [a,b].

Input

The input contains several test cases. Each test case consists of two non-negative integer numbers a and b. Input is terminated by a=b=0. Otherwise, a<=b<=10¹⁰⁰. The numbers a and b are given with no superfluous leading zeros.

Output

For each test case output on a single line the number of Fibonacci numbers fi with a<=fi<=b.

Sample Input

10 100
1234567890 9876543210
0 0

Sample Output

5
4

网上的博弈题分类中出了一个叛徒...明明不是博弈。java顺手ac了。

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

public class Main {
    public static void main(String args[]) {
        BigInteger a, b;
        Scanner in = new Scanner(System.in);
        while(in.hasNext()) {
            a = in.nextBigInteger();
            b = in.nextBigInteger();
            if(a.equals(BigInteger.ZERO) && b.equals(BigInteger.ZERO)) break;
            int cnt = 0;
            BigInteger f[] = new BigInteger[5000];
            f[1] = BigInteger.valueOf(1); f[2] = BigInteger.valueOf(2);
            for(int i = 1; ; i++) {
                if(i >= 3)
                    f[i] = f[i - 1].add(f[i - 2]);
                if(f[i].compareTo(b) > 0) break;
                if(a.compareTo(f[i]) <= 0) {
                    cnt++;
                }
            }
            System.out.println(cnt);
        }
    }
}