UVA10183-How Many Fibs? (Java large number + two points)

UVA10183-How Many Fibs? (Java large number + two points)

UVA10183-How Many Fibs? (Java large number + two points)

Question Link

Question: How many fiber numbers are there between a and B.

Solution: although a. B is very large, there are no more than 100 fibs in 10 ^ 500. In this way, we can first save these S in the array, and then find the location of a and B in the binary system each time, and then we can get the number of fibs between them.

Code:

import java.util.*;import java.math.*;import java.io.*;import java.lang.String.*;public class Main {    static BigInteger f[] = new BigInteger[10005];    static int n = 2;    public static void init () {        f[1] = BigInteger.valueOf(1);        f[2] = BigInteger.valueOf(2);        BigInteger c = BigInteger.valueOf(10).pow(100);        for (int i = 3; f[i - 1].compareTo(c) != 1; i++) {            f[i] = f[i - 1].add(f[i - 2]);            n++;        }    }    public static int upper_bound(BigInteger a) {        int l = 1;        int r = n;        int m, num;        while (l < r) {            m = (l + r) / 2;            num = a.compareTo(f[m]);            if (num <= 0)                r = m;            else                l = m + 1;        }        return r;             }    public static void main(String args[]) {        Scanner cin = new Scanner(System.in);        init();        BigInteger a, b;        while (cin.hasNext()) {            a = cin.nextBigInteger();            b = cin.nextBigInteger();            if (a.equals(BigInteger.ZERO) && b.equals(BigInteger.ZERO))                break;            int x = upper_bound(b);            int y = upper_bound(a) - 1;            if (f[x].compareTo(b) != 0)                x--;            System.out.println(x - y);                        }    }}