Problem p02652 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Pld = pair<ld, ld>;
using Vec = vector<ll>;
using VecP = vector<P>;
using VecB = vector<bool>;
using VecC = vector<char>;
using VecD = vector<ld>;
using VecS = vector<string>;
using Graph = vector<VecP>;
template <typename T> using Vec1 = vector<T>;
template <typename T> using Vec2 = vector<Vec1<T>>;
#define REP(i, m, n) for (ll i = (m); (i) < (n); ++(i))
#define REPN(i, m, n) for (ll i = (m); (i) <= (n); ++(i))
#define REPR(i, m, n) for (ll i = (m)-1; (i) >= (n); --(i))
#define REPNR(i, m, n) for (ll i = (m); (i) >= (n); --(i))
#define rep(i, n) REP(i, 0, n)
#define repn(i, n) REPN(i, 1, n)
#define repr(i, n) REPR(i, n, 0)
#define repnr(i, n) REPNR(i, n, 1)
#define all(s) (s).begin(), (s).end()
#define pb push_back
#define fs first
#define sc second
template <typename T> bool chmax(T &a, const T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> bool chmin(T &a, const T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> ll pow2(const T n) { return (1LL << n); }
template <typename T> void cosp(const T n) { cout << n << ' '; }
void co(void) { cout << '\\n'; }
template <typename T> void co(const T n) { cout << n << '\\n'; }
template <typename T1, typename T2> void co(pair<T1, T2> p) {
  cout << p.fs << ' ' << p.sc << '\\n';
}
template <typename T> void co(const Vec1<T> &v) {
  for (T i : v)
    cosp(i);
  co();
}
template <typename T> void co(initializer_list<T> v) {
  for (T i : v)
    cosp(i);
  co();
}
template <typename T> void ce(const T n) { cerr << n << endl; }
void sonic() {
  ios::sync_with_stdio(false);
  cin.tie(0);
}
void setp(const ll n) { cout << fixed << setprecision(n); }
constexpr int INF = 1e9 + 1;
constexpr ll LINF = 1e18 + 1;
constexpr ll MOD = 1e9 + 7;
// constexpr ll MOD = 998244353;
constexpr ld EPS = 1e-11;
const ld PI = acos(-1);

int main(void) {
  string s;
  cin >> s;
  ll n = s.size();
  Vec cs(n + 1);
  repr(i, n) {
    if (s[i] == '1')
      cs[i] = cs[i + 1] + 1;
    else
      cs[i] = max(0LL, cs[i + 1] - 1);
  }
  // co(cs);

  rep(m, 100) {
    bitset<101> bits(0), range(0);
    rep(i, m + 1) bits.set(i);
    rep(i, m + 1) range.set(i);
    repr(i, n) {
      bitset<101> nxt(0);
      if (s[i] == '0')
        nxt |= bits >> 1;
      else if (s[i] == '1')
        nxt |= bits << 1;
      else {
        nxt |= bits << 1;
        nxt |= bits >> 1;
      }
      nxt &= range;
      swap(nxt, bits);
      // co({i, (ll)bits.to_ullong()});
    }

    if (bits != bitset<101>(0)) {
      co(m);
      return 0;
    }
  }

  ll l = -1, r = n;
  ll ans = n;
  while (r - l > 1) {
    ll m = (l + r) / 2;
    ll p = 0, min = 0;
    bool flg = true;
    rep(i, n) {
      if (s[i] == '1')
        ++p;
      else if (s[i] == '0')
        --p;
      else {
        if (p + 1 + cs[i + 1] <= m)
          ++p;
        else
          --p;
      }
      // co({s[i]});
      // co({m, i, p});
      if (p > m) {
        flg = false;
        break;
      }
      chmin(min, p);
    }

    if (flg) {
      chmin(ans, m - min);
      r = m;
    } else
      l = m;
  }
  // co(r);
  co(ans);

  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Pld = pair<ld, ld>;
using Vec = vector<ll>;
using VecP = vector<P>;
using VecB = vector<bool>;
using VecC = vector<char>;
using VecD = vector<ld>;
using VecS = vector<string>;
using Graph = vector<VecP>;
template <typename T> using Vec1 = vector<T>;
template <typename T> using Vec2 = vector<Vec1<T>>;
#define REP(i, m, n) for (ll i = (m); (i) < (n); ++(i))
#define REPN(i, m, n) for (ll i = (m); (i) <= (n); ++(i))
#define REPR(i, m, n) for (ll i = (m)-1; (i) >= (n); --(i))
#define REPNR(i, m, n) for (ll i = (m); (i) >= (n); --(i))
#define rep(i, n) REP(i, 0, n)
#define repn(i, n) REPN(i, 1, n)
#define repr(i, n) REPR(i, n, 0)
#define repnr(i, n) REPNR(i, n, 1)
#define all(s) (s).begin(), (s).end()
#define pb push_back
#define fs first
#define sc second
template <typename T> bool chmax(T &a, const T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> bool chmin(T &a, const T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T> ll pow2(const T n) { return (1LL << n); }
template <typename T> void cosp(const T n) { cout << n << ' '; }
void co(void) { cout << '\\n'; }
template <typename T> void co(const T n) { cout << n << '\\n'; }
template <typename T1, typename T2> void co(pair<T1, T2> p) {
  cout << p.fs << ' ' << p.sc << '\\n';
}
template <typename T> void co(const Vec1<T> &v) {
  for (T i : v)
    cosp(i);
  co();
}
template <typename T> void co(initializer_list<T> v) {
  for (T i : v)
    cosp(i);
  co();
}
template <typename T> void ce(const T n) { cerr << n << endl; }
void sonic() {
  ios::sync_with_stdio(false);
  cin.tie(0);
}
void setp(const ll n) { cout << fixed << setprecision(n); }
constexpr int INF = 1e9 + 1;
constexpr ll LINF = 1e18 + 1;
constexpr ll MOD = 1e9 + 7;
// constexpr ll MOD = 998244353;
constexpr ld EPS = 1e-11;
const ld PI = acos(-1);

int main(void) {
  string s;
  cin >> s;
  ll n = s.size();
  Vec cs(n + 1);
  repr(i, n) {
    if (s[i] == '1')
      cs[i] = cs[i + 1] + 1;
    else
      cs[i] = max(0LL, cs[i + 1] - 1);
  }
  // co(cs);

  rep(m, 50) {
    bitset<2005> bits(0), range(0);
    rep(i, m + 1) bits.set(i);
    rep(i, m + 1) range.set(i);
    repr(i, n) {
      bitset<2005> nxt(0);
      if (s[i] == '0')
        nxt |= bits >> 1;
      else if (s[i] == '1')
        nxt |= bits << 1;
      else {
        nxt |= bits << 1;
        nxt |= bits >> 1;
      }
      nxt &= range;
      swap(nxt, bits);
      // co({i, (ll)bits.to_ullong()});
    }

    if (bits != bitset<2005>(0)) {
      co(m);
      return 0;
    }
  }

  ll l = -1, r = n;
  ll ans = n;
  while (r - l > 1) {
    ll m = (l + r) / 2;
    ll p = 0, min = 0;
    bool flg = true;
    rep(i, n) {
      if (s[i] == '1')
        ++p;
      else if (s[i] == '0')
        --p;
      else {
        if (p + 1 + cs[i + 1] <= m)
          ++p;
        else
          --p;
      }
      // co({s[i]});
      // co({m, i, p});
      if (p > m) {
        flg = false;
        break;
      }
      chmin(min, p);
    }

    if (flg) {
      chmin(ans, m - min);
      r = m;
    } else
      l = m;
  }
  // co(r);
  co(ans);

  return 0;
}