Submission #1025963

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Source Code Expand

#include <bits/stdc++.h>
 
#define REP(i,n) for(int i=0; i<(int)(n); ++i)
#define RREP(i,n) for(int i=(int)(n); i>=0; --i)
#define FOR(i,k,n) for(int i=(k);i<(int)(n);++i)
typedef long long int ll;
using namespace std;

int cnt[] = {0, 1, 2, 3, 4, 4, 5, 6, 7, 8};

ll f(ll n) {
    if(n == 0) return 0;

    ll size = 1;
    ll ok = 1;
    while(n/size >= 10) {
        size *= 10;
        ok *= 8;
    }
    ll msd = n / size;

    ll ret = size * msd - ok * cnt[msd];

    ll rem_digit = n - msd * size;

    if(msd == 4 || msd == 9) {
        return ret + (rem_digit + 1);
    } else {
        return ret + f(rem_digit);
    }
}


int main(void) {
    ll A, B;
    cin >> A >> B;
    cout << f(B) - f(A-1) << endl;
}

Submission Info

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