Submission #735406

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Source Code Expand

#include <iostream>
#include <string>

using namespace std;
typedef unsigned long long ull;


ull count49(string);
string decrement(string);

int main(void){
    string A, B;
    string A_;

    cin >> A >> B;
    A_ = decrement(A);
    cout << count49(B)-count49(A_) << endl;

    return 0;
}


string decrement(string s){
    int i;

    for (i=s.length()-1; i>-1; i--) {
        if (s[i] == '0') {
            s[i] = '9';
        } else {
            s[i]--;
            break;
        }
    }

    return s;
}

ull count49(string s){
    ull n=0;
    ull m=0;
    bool has_invalid_digit=false;
    unsigned int i;

    for (i=0; i<s.length(); i++) {
        n *= 8;
        m *= 10;
        m += s[i] - '0';

        if (has_invalid_digit) {
            n += 7;
        } else if (s[i] == '4') {
            n += 3;
            has_invalid_digit = true;
        } else if (s[i] == '9') {
            n += 7;
            has_invalid_digit = true;
        } else if (s[i] < '4') {
            n += s[i] - '0';
        } else if (s[i] < '9') {
            n += s[i] - '1';
        }
    }

    return m-n;
}

Submission Info

Judge Result