Problem p02581 (C++) — buggy submission, verdict: Time Limit Exceeded

///////////////////////////////////////////////////////////////////////////////

#include <bits/stdc++.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

using namespace std;

///////////////////////////////////////////////////////////////////////////////

#define DEBUG 0

#define pb push_back
#define V vector
#define M unordered_map
#define S static

#define rep(i, n) for (ll i = 0LL; i < n; ++i)
#define srep(i, s, n) for (ll i = s; i < n; ++i)
#define rrep(i, n) for (ll i = n - 1LL; i >= 0LL; --i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define CIN(x)                                                                 \\
  do {                                                                         \\
    assert(!cin.eof());                                                        \\
    cin >> x;                                                                  \\
    assert(!cin.fail());                                                       \\
  } while (0);
#if DEBUG
#define debug_print(...) _debug_print(__VA_ARGS__)
#define debug_printf(...) printf(__VA_ARGS__)
#define debug_print_time _debug_print_time
#else // DEBUG
#define debug_print(...)
#define debug_printf(...)
#define debug_print_time
#endif // DEBUG

typedef long long ll;
typedef unsigned long long ull;
typedef tuple<ll, ll> t2;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;
template <typename T>
using priority_queue_incr = priority_queue<T, V<T>, greater<T>>;

///////////////////////////////////////////////////////////////////////////////

template <typename TT, typename T> T get_m(M<TT, T> &m, TT k, T default_value) {
  if (m.find(k) == m.end())
    return m[k] = default_value;
  return m[k];
}

template <typename TT, typename T> void incr_m(M<TT, T> &m, TT k) {
  if (m.find(k) == m.end())
    m[k] = 0;
  m[k]++;
}

template <typename TT, typename T> void incr_m(map<TT, T> &m, TT k) {
  if (m.find(k) == m.end())
    m[k] = 0;
  m[k]++;
}

void llin(ll &a) { CIN(a); }

void llinl1(V<ll> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a;
    CIN(a);
    v.push_back(a);
  }
}

void llinl2(V<t2> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b;
    CIN(a >> b);
    v.push_back(t2(a, b));
  }
}

void llinl3(V<t3> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b, c;
    CIN(a >> b >> c);
    v.push_back(t3(a, b, c));
  }
}

void llinl4(V<t4> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b, c, d;
    CIN(a >> b >> c >> d);
    v.push_back(t4(a, b, c, d));
  }
}

void llina(V<ll> &v, ll count) { llinl1(v, count); }

template <typename T> void sort(V<T> &v) { sort(v.begin(), v.end()); }

template <typename T> void sort_reverse(V<T> &v) {
  sort(v.begin(), v.end(), greater<T>());
}

template <typename T> void _debug_print(T x) { cout << x << endl; }

void _debug_print(const t2 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  cout << "-- " << x1 << " -- " << x2 << endl;
}

void _debug_print(const t3 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  ll x3 = get<2>(x);
  cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << endl;
}

void _debug_print(const t4 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  ll x3 = get<2>(x);
  ll x4 = get<3>(x);
  cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << " -- " << x4 << endl;
}

template <typename T> void _debug_print(T xarray[], ll n) {
  rep(i, n) _debug_print(xarray[i]);
}

template <typename T> void _debug_print(const V<T> &xlist) {
  for (auto x : xlist) {
    cout << "-- ";
    _debug_print(x);
  }
}

template <typename T> void _debug_print(const set<T> &xset) {
  for (auto x : xset) {
    cout << "-- ";
    _debug_print(x);
  }
}

template <typename TT, typename T> void _debug_print(const M<TT, T> &xlist) {
  for (auto x : xlist) {
    TT k = x.first;
    T v = x.second;
    cout << "====" << endl;
    cout << "K=";
    _debug_print(k);
    cout << "V=";
    _debug_print(v);
  }
}

template <typename TT, typename T> void _debug_print(const map<TT, T> &xlist) {
  for (auto x : xlist) {
    TT k = x.first;
    T v = x.second;
    cout << "====" << endl;
    cout << "K=";
    _debug_print(k);
    cout << "V=";
    _debug_print(v);
  }
}

void _debug_print_time(const char *prefix) {
  struct timeval tv;
  gettimeofday(&tv, NULL);
#if DEBUG
  struct tm *tm = localtime(&tv.tv_sec);
#endif
  debug_printf("-- %s %02d:%02d:%02d.%06ld\\n", prefix, tm->tm_hour, tm->tm_min,
               tm->tm_sec, tv.tv_usec);
}

///////////////////////////////////////////////////////////////////////////////

void _main();
int main() {
  cout << setprecision(12);
#if !DEBUG
  ios::sync_with_stdio(false);
  cin.tie(0);
#endif

  _main();
  return 0;
}

S ll cnts[2005][2005];
S ll maxcnts[2005];
S ll updated[2005][2005];
S V<t2> updated_idxs;

void f_cnts(ll idx0, ll idx1, ll val) {
  cnts[idx0][idx1] = max(cnts[idx0][idx1], val);
  maxcnts[idx0] = max(maxcnts[idx0], val);
  cnts[idx1][idx0] = max(cnts[idx1][idx0], val);
  maxcnts[idx1] = max(maxcnts[idx1], val);
}

void f_updated(ll idx0, ll idx1, ll val) {
  updated[idx0][idx1] = max(updated[idx0][idx1], val);
  updated[idx1][idx0] = max(updated[idx1][idx0], val);
  updated_idxs.pb(t2(idx0, idx1));
}

void _main() {
  ll n;
  llin(n);
  V<ll> alist;
  llina(alist, 3LL * n);

  rep(i, 2005) rep(j, 2005) cnts[i][j] = -1e18;
  rep(i, 2005) maxcnts[i] = -1e18;
  rep(i, 2005) rep(j, 2005) updated[i][j] = -1e18;
  f_cnts(alist[0], alist[1], 0);

  ll bonus = 0;

  rep(i, n - 1) {
    debug_printf("-------------\\n");
    debug_printf("---- cnts[1]\\n");
    debug_print(cnts[1], 3);
    debug_printf("---- cnts[2]\\n");
    debug_print(cnts[2], 3);

    ll a0 = alist[i * 3 + 2];
    ll a1 = alist[i * 3 + 3];
    ll a2 = alist[i * 3 + 4];

    if (a0 == a1 && a1 == a2) {
      bonus++;
      continue;
    }

    ll allmax = -1e18;
    rep(j, 2005) allmax = max(allmax, maxcnts[j]);

    V<ll> as;
    as.pb(a0);
    as.pb(a1);
    as.pb(a2);
    updated_idxs.clear();

    rep(j, 3) {
      ll discard = as[j];
      ll remain0 = as[(j + 1) % 3];
      ll remain1 = as[(j + 2) % 3];
      ll newval = max(cnts[discard][discard] + 1LL, allmax);
      f_updated(remain0, remain1, newval);
    }

    rep(j, 3) {
      ll remain = as[j];
      ll discard0 = as[(j + 1) % 3];
      ll discard1 = as[(j + 2) % 3];
      rep(b, 2005) f_updated(remain, b, maxcnts[b]);
      if (discard0 == discard1) {
        rep(b, 2005) f_updated(remain, b, cnts[b][discard0] + 1LL);
      }
    }

    for (auto updated_idxs : updated_idxs) {
      ll idx0 = get<0>(updated_idxs);
      ll idx1 = get<1>(updated_idxs);
      f_cnts(idx0, idx1, updated[idx0][idx1]);
    }
  }

  debug_printf("-------------\\n");
  debug_printf("---- cnts[1]\\n");
  debug_print(cnts[1], 3);
  debug_printf("---- cnts[2]\\n");
  debug_print(cnts[2], 3);

  ll la = alist[3 * n - 1];
  cnts[la][la]++;

  ll ans = -1e18;
  rep(i, 2005) rep(j, 2005) ans = max(ans, cnts[i][j]);
  ans += bonus;

  debug_printf("-------- ans\\n");
  cout << ans << endl;
}

///////////////////////////////////////////////////////////////////////////////


Error: TLE

Fixed submission:

///////////////////////////////////////////////////////////////////////////////

#include <bits/stdc++.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

using namespace std;

///////////////////////////////////////////////////////////////////////////////

#define DEBUG 0

#define pb push_back
#define V vector
#define M unordered_map
#define S static

#define rep(i, n) for (ll i = 0LL; i < n; ++i)
#define srep(i, s, n) for (ll i = s; i < n; ++i)
#define rrep(i, n) for (ll i = n - 1LL; i >= 0LL; --i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define CIN(x)                                                                 \\
  do {                                                                         \\
    assert(!cin.eof());                                                        \\
    cin >> x;                                                                  \\
    assert(!cin.fail());                                                       \\
  } while (0);
#if DEBUG
#define debug_print(...) _debug_print(__VA_ARGS__)
#define debug_printf(...) printf(__VA_ARGS__)
#define debug_print_time _debug_print_time
#else // DEBUG
#define debug_print(...)
#define debug_printf(...)
#define debug_print_time
#endif // DEBUG

typedef long long ll;
typedef unsigned long long ull;
typedef tuple<ll, ll> t2;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;
template <typename T>
using priority_queue_incr = priority_queue<T, V<T>, greater<T>>;

///////////////////////////////////////////////////////////////////////////////

template <typename TT, typename T> T get_m(M<TT, T> &m, TT k, T default_value) {
  if (m.find(k) == m.end())
    return m[k] = default_value;
  return m[k];
}

template <typename TT, typename T> void incr_m(M<TT, T> &m, TT k) {
  if (m.find(k) == m.end())
    m[k] = 0;
  m[k]++;
}

template <typename TT, typename T> void incr_m(map<TT, T> &m, TT k) {
  if (m.find(k) == m.end())
    m[k] = 0;
  m[k]++;
}

void llin(ll &a) { CIN(a); }

void llinl1(V<ll> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a;
    CIN(a);
    v.push_back(a);
  }
}

void llinl2(V<t2> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b;
    CIN(a >> b);
    v.push_back(t2(a, b));
  }
}

void llinl3(V<t3> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b, c;
    CIN(a >> b >> c);
    v.push_back(t3(a, b, c));
  }
}

void llinl4(V<t4> &v, ll count) {
  for (ll i = 0LL; i < count; ++i) {
    ll a, b, c, d;
    CIN(a >> b >> c >> d);
    v.push_back(t4(a, b, c, d));
  }
}

void llina(V<ll> &v, ll count) { llinl1(v, count); }

template <typename T> void sort(V<T> &v) { sort(v.begin(), v.end()); }

template <typename T> void sort_reverse(V<T> &v) {
  sort(v.begin(), v.end(), greater<T>());
}

template <typename T> void _debug_print(T x) { cout << x << endl; }

void _debug_print(const t2 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  cout << "-- " << x1 << " -- " << x2 << endl;
}

void _debug_print(const t3 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  ll x3 = get<2>(x);
  cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << endl;
}

void _debug_print(const t4 &x) {
  ll x1 = get<0>(x);
  ll x2 = get<1>(x);
  ll x3 = get<2>(x);
  ll x4 = get<3>(x);
  cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << " -- " << x4 << endl;
}

template <typename T> void _debug_print(T xarray[], ll n) {
  rep(i, n) _debug_print(xarray[i]);
}

template <typename T> void _debug_print(const V<T> &xlist) {
  for (auto x : xlist) {
    cout << "-- ";
    _debug_print(x);
  }
}

template <typename T> void _debug_print(const set<T> &xset) {
  for (auto x : xset) {
    cout << "-- ";
    _debug_print(x);
  }
}

template <typename TT, typename T> void _debug_print(const M<TT, T> &xlist) {
  for (auto x : xlist) {
    TT k = x.first;
    T v = x.second;
    cout << "====" << endl;
    cout << "K=";
    _debug_print(k);
    cout << "V=";
    _debug_print(v);
  }
}

template <typename TT, typename T> void _debug_print(const map<TT, T> &xlist) {
  for (auto x : xlist) {
    TT k = x.first;
    T v = x.second;
    cout << "====" << endl;
    cout << "K=";
    _debug_print(k);
    cout << "V=";
    _debug_print(v);
  }
}

void _debug_print_time(const char *prefix) {
  struct timeval tv;
  gettimeofday(&tv, NULL);
#if DEBUG
  struct tm *tm = localtime(&tv.tv_sec);
#endif
  debug_printf("-- %s %02d:%02d:%02d.%06ld\\n", prefix, tm->tm_hour, tm->tm_min,
               tm->tm_sec, tv.tv_usec);
}

///////////////////////////////////////////////////////////////////////////////

void _main();
int main() {
  cout << setprecision(12);
#if !DEBUG
  ios::sync_with_stdio(false);
  cin.tie(0);
#endif

  _main();
  return 0;
}

S ll cnts[2005][2005];
S ll maxcnts[2005];

void f_cnts(ll idx0, ll idx1, ll val) {
  cnts[idx0][idx1] = max(cnts[idx0][idx1], val);
  maxcnts[idx0] = max(maxcnts[idx0], val);
  cnts[idx1][idx0] = max(cnts[idx1][idx0], val);
  maxcnts[idx1] = max(maxcnts[idx1], val);
}

void f_updated(map<t2, ll> &updated, ll idx0, ll idx1, ll val) {
  if (updated.find(t2(idx0, idx1)) == updated.end()) {
    updated[t2(idx0, idx1)] = val;
    updated[t2(idx1, idx0)] = val;
    return;
  }
  updated[t2(idx0, idx1)] = max(updated[t2(idx0, idx1)], val);
  updated[t2(idx1, idx0)] = max(updated[t2(idx1, idx0)], val);
}

void _main() {
  ll n;
  llin(n);
  V<ll> alist;
  llina(alist, 3LL * n);

  rep(i, 2005) rep(j, 2005) cnts[i][j] = -1e18;
  rep(i, 2005) maxcnts[i] = -1e18;
  f_cnts(alist[0], alist[1], 0);

  ll bonus = 0;

  rep(i, n - 1) {
    debug_printf("-------------\\n");
    debug_printf("---- cnts[1]\\n");
    debug_print(cnts[1], 3);
    debug_printf("---- cnts[2]\\n");
    debug_print(cnts[2], 3);

    ll a0 = alist[i * 3 + 2];
    ll a1 = alist[i * 3 + 3];
    ll a2 = alist[i * 3 + 4];

    if (a0 == a1 && a1 == a2) {
      bonus++;
      continue;
    }

    ll allmax = -1e18;
    rep(j, 2005) allmax = max(allmax, maxcnts[j]);

    map<t2, ll> updated;
    V<ll> as;
    as.pb(a0);
    as.pb(a1);
    as.pb(a2);

    rep(j, 3) {
      ll discard = as[j];
      ll remain0 = as[(j + 1) % 3];
      ll remain1 = as[(j + 2) % 3];
      ll newval = max(cnts[discard][discard] + 1LL, allmax);
      f_updated(updated, remain0, remain1, newval);
    }

    rep(j, 3) {
      ll remain = as[j];
      ll discard0 = as[(j + 1) % 3];
      ll discard1 = as[(j + 2) % 3];
      rep(b, 2005) f_updated(updated, remain, b, maxcnts[b]);
      if (discard0 == discard1) {
        rep(b, 2005) f_updated(updated, remain, b, cnts[b][discard0] + 1LL);
      }
    }

    for (auto item : updated) {
      ll idx0 = get<0>(item.first);
      ll idx1 = get<1>(item.first);
      ll newcnt = item.second;
      f_cnts(idx0, idx1, newcnt);
    }
  }

  debug_printf("-------------\\n");
  debug_printf("---- cnts[1]\\n");
  debug_print(cnts[1], 3);
  debug_printf("---- cnts[2]\\n");
  debug_print(cnts[2], 3);

  ll la = alist[3 * n - 1];
  cnts[la][la]++;

  ll ans = -1e18;
  rep(i, 2005) rep(j, 2005) ans = max(ans, cnts[i][j]);
  ans += bonus;

  debug_printf("-------- ans\\n");
  cout << ans << endl;
}

///////////////////////////////////////////////////////////////////////////////