How Many Fibs_hdu_1316(大数).java

时间:2021-08-22 12:10:44

How Many Fibs?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3098    Accepted Submission(s): 1232

Problem Description
Recall the definition of the Fibonacci numbers: 

f1 := 1 

f2 := 2 

fn := fn-1 + fn-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 <= 10^100. 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

import java.math.BigInteger;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
BigInteger f[]=new BigInteger[505];
f[0]=BigInteger.valueOf(1);
f[1]=BigInteger.valueOf(2);
for(int i=2;i<502;i++){
f[i]=f[i-1].add(f[i-2]);
}
while(true){
BigInteger a=input.nextBigInteger();
BigInteger b=input.nextBigInteger();
if(a.equals(BigInteger.ZERO)&&b.equals(BigInteger.ZERO))
break;
int sum=0;
for(int i=0;i<502&&b.compareTo(f[i])>=0;i++){
if(f[i].compareTo(a)>=0)
sum++;
}
System.out.println(sum);
}
}
}