Onnenluku

#include <iostream>
#include <set>
#include <vector>
#include <cstring>
using namespace std;
typedef long long ll;
ll f(vector<int> x) {
    ll ans = 0;
    vector<int> q;
    for(int i = 1; i < (int)x.size()-1; ++i) {
        for(int j = 1; j <= 9; ++j) {
            ans += ((1ll<<i)-1)*8;
        }
    }
    for(int i = (int)x.size()-1; i >= 0; --i) {
        int y = x[i];
        //cout<<ans<<' '<<y<<'\n';
        if(q.size() == 0) {
            for(int j = 1; j < y; ++j) {
                ans += ((1ll<<i)-1)*8;
            }
            q.push_back(y);
        }
        else if(q.size() == 1) {
            for(int j = 1; j < y; ++j) {
                if(j == q[0]) {
                    ans += ((1ll<<i)-1)*8;
                }
                else {
                    ans += ((1ll<<i));
                }
            }
            if(q[0] != y) {
                q.push_back(y);
                if(y == 0) {
                    q.push_back(y);
                    break;
                }
            }
        }
        else if(q.size() == 2) {
            for(int j = 1; j < y; ++j) {
                if(j == q[0]) {
                    ans += ((1ll<<i));
                }
                if(j == q[1]) {
                    ans += ((1ll<<i));
                }
            }
            if(q[0] != y && q[1] != y) {
                q.push_back(y);
            }
        }
        else {
            break;
        }
    }
    if(q.size() == 2 && q[0] != 0 && q[1] != 0) ++ans;
    return ans;


}
int main() {
    string a,b;
    cin>>a>>b;
    vector<int> aa, bb;
    set<int> lol;
    for(int i = a.size()-1; i >= 0; --i) {
        aa.push_back(a[i]-'0');
        lol.insert(aa.back());
    }
    for(int i = b.size()-1; i >= 0; --i) {
        bb.push_back(b[i]-'0');
    }
//    cout<<bb.size()<<'\n';
//cout<<f(bb)<<'\n';
    cout<<f(bb)-f(aa)+(lol.size()==2 && *lol.begin() != 0)<<'\n';
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED