Bittijono

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

ll alijonot(string bj) {
    ll maara = 0;
    ll uusia0 = 1;
    ll uusia1 = 1;
    for (unsigned long long i = 0; i < bj.length(); i++) {
        char c = bj[i];
        if (c == '1') {
            maara += uusia1;
            uusia0 += uusia1;
        } else {
            maara += uusia0;
            uusia1 += uusia0;
        }
    }
    return maara;
}

int main() {
  ios_base::sync_with_stdio(false);
  ll tavoite;
  cin >> tavoite;

  ll minimi = 1;
  ll maksimi = 28;
  while (minimi != maksimi) {
      ll pituus = ll((minimi + maksimi) / 2);
      ll arvo = 1;
      for (ll i = 0; i < pituus - 1; i++) {
          arvo*=2;
          arvo+=(i%2);
      }
      string jono = bitset<29>(arvo).to_string();
      jono.erase(0, 29 - pituus);
      if (alijonot(jono) >= tavoite) {
          maksimi = pituus;
      } else {
          minimi = pituus + 1;
      }
  }
  ll pituus = minimi;
  ll alku = pow(2, pituus - 1);
  ll loppu = 2*alku;
  set<ll> kaytetyt;
  while (true) {
      int mod = (alku + 1) % 3;
      for (ll i = alku; i < loppu; i++) {
          if (tavoite % 2 == 0) {
              if (i % 3 != mod) {
                  continue;
              }
          } else if (i % 3 == mod) {
              continue;
          }
          if (kaytetyt.count(i) != 0) {
              continue;
          }
          string jono = bitset<30>(i).to_string();
          jono.erase(0, 30 - pituus);
        // if (kaytetyt.count(jono) != 0) {
        //     continue;
        // }
          if (alijonot(jono) == tavoite) {
              cout << jono << endl;
              return 0;
          }
          if (i % 2 != 0) {
              reverse(jono.begin(),jono.end());
              bitset<30> bits;
              istringstream is(jono);
              is >> bits;
              kaytetyt.insert(bits.to_ulong());
          } else {
              jono = bitset<30>(loppu-1-i).to_string();
              jono.erase(0, 30-pituus);
              reverse(jono.begin(),jono.end());
              bitset<30> bits;
              istringstream is(jono);
              is >> bits;
              kaytetyt.insert(bits.to_ulong());
          }
      }
      alku = loppu;
      loppu *= 2;
      pituus += 1;
  }
}

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: 1

Verdict: ACCEPTED

Test 7

Group: 1

Verdict: ACCEPTED

Test 8

Group: 1

Verdict: ACCEPTED

Test 9

Group: 1

Verdict: ACCEPTED

Test 10

Group: 1

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED

Test 16

Group: 2

Verdict: ACCEPTED

Test 17

Group: 2

Verdict: ACCEPTED

Test 18

Group: 2

Verdict: ACCEPTED

Test 19

Group: 2

Verdict: ACCEPTED

Test 20

Group: 2

Verdict: ACCEPTED

Test 21

Group: 3

Verdict: ACCEPTED

Test 22

Group: 3

Verdict: ACCEPTED

Test 23

Group: 3

Verdict: ACCEPTED

Test 24

Group: 3

Verdict: ACCEPTED

Test 25

Group: 3

Verdict: ACCEPTED

Test 26

Group: 3

Verdict: ACCEPTED

Test 27

Group: 3

Verdict: ACCEPTED

Test 28

Group: 3

Verdict: ACCEPTED

Test 29

Group: 3

Verdict: ACCEPTED

Test 30

Group: 3

Verdict: ACCEPTED

Test 31

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 32

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 33

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 34

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 35

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 36

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 37

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 38

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 39

Group: 4

Verdict: TIME LIMIT EXCEEDED

Test 40

Group: 4

Verdict: TIME LIMIT EXCEEDED