uva 10183 - How Many Fibs?（Fibonacci)

Problem B: How many Fibs?

Recall the definition of the Fibonacci numbers:

f₁ := 1 
f₂ := 2 
f_n := 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 Specification

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 Specification

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

Sample Input

10 1001234567890 98765432100 0

Sample Output

54

#include <iostream>#include <cstdio>#include <string>#include <algorithm>#include <vector>using namespace std;const int maxn = 1000;string F[maxn] , a , b;string add(string n1 , string n2){    int len1 = n1.length() , len2 = n2.length() , carry = 0;    string result;    for(int i = len1-1 , j = len2-1; i >= 0 || j >= 0; i-- , j--){        int sum = carry;        if(i >= 0) sum += n1[i]-'0';        if(j >= 0) sum += n2[j]-'0';        carry = sum/10;        sum = sum%10;        result.push_back(char('0'+sum));    }    if(carry) result.push_back(char('0'+carry));    reverse(result.begin() , result.end());    return result;}void Fibonacci(){    F[0] = "1";    F[1] = "2";    for(int i = 2; i < maxn; i++){        F[i] = add(F[i-1] , F[i-2]);    }}bool is_larger(string n1 , string n2){    int len1 = n1.length() , len2 = n2.length();    if(len1 > len2) return true;    if(len1 < len2) return false;    for(int i = 0; i < len1; i++){        if(n1[i]-'0' > n2[i]-'0') return true;        if(n1[i]-'0' < n2[i]-'0') return false;    }    return false;}int Binary_search(string num){    int l = 0 , r = 1000;    while(l < r){        int mid = (l+r)/2;        if(is_larger(F[mid] , num)){            r = mid;        }else{            l = mid+1;        }    }    return r;}void computing(){    int l = Binary_search(a), r = Binary_search(b)-1;    if(l > 0 && F[l-1] == a){        l--;    }    printf("%d\n" , r-l+1);}int main(){    Fibonacci();    while(cin >> a >> b && (a != "0" || b != "0")){        computing();    }    return 0;}