HDU1316 How Many Fibs? 【大数】

原题链接

import java.util.Scanner;
import java.math.BigInteger;

public class Main{
	static final int max = 500;
	static BigInteger[] arr = new BigInteger[max];
	public static void main(String[] args){
		Scanner cin = new Scanner(System.in);		
		BigInteger a,b;		
		int i,l,r;
		arr[1] = BigInteger.ONE; arr[2] = BigInteger.valueOf(2);
		for(i = 3; i != max; ++i)
			arr[i] = arr[i - 1].add(arr[i - 2]);
		while(true){
			a = cin.nextBigInteger();
			b = cin.nextBigInteger();
			if(a.compareTo(BigInteger.ZERO) == 0 
				&& b.compareTo(BigInteger.ZERO) == 0) break;
			l = binarySearch1(a);
			r = binarySearch2(b);
			System.out.println(r - l);
		}
	}
	
	public static int binarySearch1(BigInteger n){
		int i;
		for(i = 1; i < max; ++i)
			if(arr[i].compareTo(n) >= 0) return i;
		return 0;
	}
	
	public static int binarySearch2(BigInteger n){
		int i;
		for(i = 1; i < max; ++i)
			if(arr[i].compareTo(n) > 0) return i;
		return 0;
	}
}