Problem p02667 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
// #define ll __int128
// #define int ll
// #define int ll
// #define char ll
#define double ld
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for (int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr                                                                   \\
  if (false)                                                                   \\
  cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
  return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
  return in >> a.first >> a.second;
}

template <class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << ", " << get<3>(a) << "}";
}

template <class T> inline ostream &operator<<(ostream &out, vector<T> &a) {
  out << "[";
  fori(i, a.size()) out << a[i]
                        << vector<string>{", ", "]  "}[i + 1 == a.size()];
  return out;
}

void smain();

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
#ifdef MAX_HOME
  freopen("input.txt", "r", stdin);
  clock_t start = clock();
#endif
  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
  return 0;
}

int get(string s, vi p) {
  int n = s.size();
  vector<bool> used(n, false);
  int cur = 0;
  for (auto pos : p) {
    used[pos] = true;
    string t = "";
    fori(i, n) if (used[i]) t += s[i];

    for (int i = 0; i < SZ(t); i += 2) {
      cur += t[i] == '1';
    }
  }
  return cur;
}

int kek(string s) {
  int n = SZ(s);

  bool odd = false;
  vi p1, p2, p3;
  fori(i, n) {
    if (s[i] == '1') {
      p1.push_back(i);
      odd ^= 1;
    } else {
      if (odd) {
        p2.push_back(i);
        odd = false;
      } else {
        p3.push_back(i);
      }
    }
  }
  reverse(ALL(p3));
  p1.insert(p1.end(), ALL(p2));
  p1.insert(p1.end(), ALL(p3));
  return get(s, p1);
}

int naive(string s) {
  int n = s.size();
  vi p(n);
  fori(i, n) { p[i] = i; }
  int ans = -1;
  vi best = p;
  do {
    int cur = get(s, p);
    if (cur > ans) {
      ans = cur;
      best = p;
    }
    if (cur == 26)
      break;
  } while (next_permutation(ALL(p)));
  //    watch(best);
  return ans;
}

void stress() {
  int cnt = -1;
  while (true) {
    if (++cnt % 2000 == 0)
      watch(cnt);
    int n = 1 + rng() % 10;
    string s(n, '0');
    fori(i, n) { s[i] = char('0' + rng() % 2); }
    if (naive(s) != kek(s)) {
      watch(s);
      return;
    }
  }
}

struct Tree {
  vector<pii> t;
  vi cnt;
  vector<int> pushing;
  Tree(int n) {
    t.resize(n << 2, {0, 0});
    pushing.resize(n << 2, false);
    cnt.resize(n << 2, 0);
  }

  void push(int v) {
    if (pushing[v]) {
      swap(t[v << 1].first, t[v << 1].second);
      swap(t[v << 1 | 1].first, t[v << 1 | 1].second);
      pushing[v << 1] ^= pushing[v];
      pushing[v << 1 | 1] ^= pushing[v];
      pushing[v] = false;
    }
  }

  void upd(int v, int tl, int tr, int pos, int val, bool odd) {
    cnt[v]++;
    if (tl == tr) {
      if (odd)
        t[v].second = val;
      else
        t[v].first = val;
      return;
    }
    push(v);
    int tm = tl + tr >> 1;
    if (pos <= tm)
      upd(v << 1, tl, tm, pos, val, odd);
    else
      upd(v << 1 | 1, tm + 1, tr, pos, val, odd);
    t[v].first = t[v << 1].first + t[v << 1 | 1].first;
    t[v].second = t[v << 1].second + t[v << 1 | 1].second;
  }

  void swp(int v, int tl, int tr, int l, int r) {
    if (l > r)
      return;
    if (tl == l && tr == r) {
      swap(t[v].first, t[v].second);
      pushing[v] ^= 1;
      return;
    }
    push(v);
    int tm = tl + tr >> 1;
    swp(v << 1, tl, tm, l, min(tm, r));
    swp(v << 1 | 1, tm + 1, tr, max(tm + 1, l), r);
    t[v].first = t[v << 1].first + t[v << 1 | 1].first;
    t[v].second = t[v << 1].second + t[v << 1 | 1].second;
  }

  int get_cnt(int v, int tl, int tr, int l, int r) {
    if (l > r)
      return 0;
    if (tl == l && tr == r)
      return cnt[v];
    push(v);
    int tm = tl + tr >> 1;
    return get_cnt(v << 1, tl, tm, l, min(tm, r)) +
           get_cnt(v << 1 | 1, tm + 1, tr, max(tm + 1, l), r);
  }
};

ll fast_get(string s, vi p) {
  int n = s.size();
  Tree tree(n);
  ll ans = 0;
  for (auto pos : p) {
    tree.upd(1, 0, n - 1, pos, s[pos] == '1',
             tree.get_cnt(1, 0, n - 1, 0, pos) & 1);
    tree.swp(1, 0, n - 1, pos + 1, n - 1);
    ans += tree.t[1].first;
  }
  return ans;
}

ll fast_kek(string s) {
  int n = SZ(s);

  bool odd = false;
  vi p1, p2, p3;
  fori(i, n) {
    if (s[i] == '1') {
      p1.push_back(i);
      odd ^= 1;
    } else {
      if (odd) {
        p2.push_back(i);
        odd = false;
      } else {
        p3.push_back(i);
      }
    }
  }
  reverse(ALL(p3));
  p1.insert(p1.end(), ALL(p2));
  p1.insert(p1.end(), ALL(p3));
  return fast_get(s, p1);
}

void smain() {

  //    stress();
  //    return;

  string s;
  cin >> s;
  cout << fast_kek(s) << '\\n';
  //    watch(naive(s));
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
// #define ll __int128
// #define int ll
// #define int ll
// #define char ll
#define double ld
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for (int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr                                                                   \\
  if (false)                                                                   \\
  cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
  return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
  return in >> a.first >> a.second;
}

template <class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << ", " << get<3>(a) << "}";
}

template <class T> inline ostream &operator<<(ostream &out, vector<T> &a) {
  out << "[";
  fori(i, a.size()) out << a[i]
                        << vector<string>{", ", "]  "}[i + 1 == a.size()];
  return out;
}

void smain();

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
#ifdef MAX_HOME
  freopen("input.txt", "r", stdin);
  clock_t start = clock();
#endif
  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
  return 0;
}

int get(string s, vi p) {
  int n = s.size();
  vector<bool> used(n, false);
  int cur = 0;
  for (auto pos : p) {
    used[pos] = true;
    string t = "";
    fori(i, n) if (used[i]) t += s[i];

    for (int i = 0; i < SZ(t); i += 2) {
      cur += t[i] == '1';
    }
  }
  return cur;
}

int kek(string s) {
  int n = SZ(s);

  bool odd = false;
  vi p1, p2, p3;
  fori(i, n) {
    if (s[i] == '1') {
      p1.push_back(i);
      odd ^= 1;
    } else {
      if (odd) {
        p2.push_back(i);
        odd = false;
      } else {
        p3.push_back(i);
      }
    }
  }
  reverse(ALL(p3));
  p1.insert(p1.end(), ALL(p2));
  p1.insert(p1.end(), ALL(p3));
  return get(s, p1);
}

int naive(string s) {
  int n = s.size();
  vi p(n);
  fori(i, n) { p[i] = i; }
  int ans = -1;
  vi best = p;
  do {
    int cur = get(s, p);
    if (cur > ans) {
      ans = cur;
      best = p;
    }
    if (cur == 26)
      break;
  } while (next_permutation(ALL(p)));
  //    watch(best);
  return ans;
}

void stress() {
  int cnt = -1;
  while (true) {
    if (++cnt % 2000 == 0)
      watch(cnt);
    int n = 1 + rng() % 10;
    string s(n, '0');
    fori(i, n) { s[i] = char('0' + rng() % 2); }
    if (naive(s) != kek(s)) {
      watch(s);
      return;
    }
  }
}

void smain() {

  //    stress();
  //    return;

  string s;
  cin >> s;
  cout << kek(s) << '\\n';
  //    watch(naive(s));
}