Problem p02581 (C++)

Buggy submission (status: Time Limit Exceeded):
#line 2 "header.hpp"

//%snippet.set('header')%
//%snippet.fold()%
#ifndef HEADER_H
#define HEADER_H

// template version 2.0
using namespace std;
#include <bits/stdc++.h>

// varibable settings
const long long INF = 1e18;
template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = (ll)(a); i < (ll)(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _rrep(i, n) rrepi(i, 0, n)
#define rrepi(i, a, b) for (ll i = (ll)((b)-1); i >= (ll)(a); --i)
#define r_rep(...) _overload3(__VA_ARGS__, rrepi, _rrep, )(__VA_ARGS__)
#define each(i, a) for (auto &&i : a)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(...) make_tuple(__VA_ARGS__)
#define ub upper_bound
#define lb lower_bound
#define lpos(A, x) (lower_bound(all(A), x) - A.begin())
#define upos(A, x) (upper_bound(all(A), x) - A.begin())
template <class T> inline void chmax(T &a, const T &b) {
  if ((a) < (b))
    (a) = (b);
}
template <class T> inline void chmin(T &a, const T &b) {
  if ((a) > (b))
    (a) = (b);
}
template <typename X, typename T> auto make_table(X x, T a) {
  return vector<T>(x, a);
}
template <typename X, typename Y, typename Z, typename... Zs>
auto make_table(X x, Y y, Z z, Zs... zs) {
  auto cont = make_table(y, z, zs...);
  return vector<decltype(cont)>(x, cont);
}

#define cdiv(a, b) (((a) + (b)-1) / (b))
#define is_in(x, a, b) ((a) <= (x) && (x) < (b))
#define uni(x)                                                                 \
  sort(all(x));                                                                \
  x.erase(unique(all(x)), x.end())
#define slice(l, r) substr(l, r - l)

typedef long long ll;
typedef long double ld;
using vl = vector<ll>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;

template <typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
void check_input() {
  assert(cin.eof() == 0);
  int tmp;
  cin >> tmp;
  assert(cin.eof() == 1);
}

#if defined(PCM) || defined(LOCAL)
#else
#define dump(...) ;
#define dump_1d(...) ;
#define dump_2d(...) ;
#define cerrendl ;
#endif

#endif /* HEADER_H */
//%snippet.end()%
#line 2 "solve2.cpp"
template <class T = ll> using vec = vector<T>;
struct Fast {
  Fast() {
    std::cin.tie(0);
    ios::sync_with_stdio(false);
  }
} fast;

void recursive_comb(int *indexes, int s, int rest,
                    std::function<void(int *)> f) {
  if (rest == 0) {
    f(indexes);
  } else {
    if (s < 0)
      return;
    recursive_comb(indexes, s - 1, rest, f);
    indexes[rest - 1] = s;
    recursive_comb(indexes, s - 1, rest - 1, f);
  }
}

// nCkの組み合わせに対して処理を実行する
void foreach_comb(int n, int k, std::function<void(int *)> f) {
  int indexes[k];
  recursive_comb(indexes, n - 1, k, f);
}

int solve() {
  ll n;
  cin >> n;
  vector<ll> a(3 * n);
  rep(i, 3 * n) {
    cin >> a[i];
    a[i]--;
  }
  dump(a);
  a.pb(n);
  a.pb(n + 1);

  vec<vec<ll>> dp = make_table(n + 2, n + 2, -INF);
  dp[a[0]][a[1]] = 0;
  dp[a[1]][a[0]] = 0;
  ll now = 2;

  vec<ll> buf(3);
  ll add = 0;
  vec<tuple<ll, ll, ll>> updates;
  vec<ll> local(n + 2, -INF);
  local[a[0]] = 0;
  local[a[1]] = 0;
  while (true) {
    cerrendl;
    dump(now);
    buf[0] = a[now];
    buf[1] = a[now + 1];
    buf[2] = a[now + 2];
    sort(all(buf));

    ll mv = *max_element(all(local));

    if (buf[0] == buf[2]) {
      add++;
    } else {
      if (buf[0] == buf[1]) {
        ll p = buf[0];
        ll q = buf[2];
        rep(x, n) updates.pb(mt(q, x, dp[p][x] + 1));
      } else if (buf[1] == buf[2]) {
        ll p = buf[1];
        ll q = buf[0];
        rep(x, n) updates.pb(mt(q, x, dp[p][x] + 1));
      }
      ll p = buf[0];
      ll q = buf[1];
      ll r = buf[2];
      updates.pb(mt(q, r, dp[p][p] + 1));
      updates.pb(mt(p, r, dp[q][q] + 1));
      updates.pb(mt(p, q, dp[r][r] + 1));

      // (2, 1)
      updates.pb(mt(p, q, mv));
      updates.pb(mt(p, r, mv));
      updates.pb(mt(r, q, mv));

      // (1, 2)
      rep(x, n) {
        updates.pb(mt(x, p, local[x]));
        updates.pb(mt(x, q, local[x]));
        updates.pb(mt(x, r, local[x]));
      }
    }

    dump(updates);
    for (auto [x, y, v] : updates) {
      chmax(dp[x][y], v);
      chmax(dp[y][x], v);
      chmax(local[x], v);
      chmax(local[y], v);
    }

    if (now == 3 * n - 1)
      break;
    now += 3;
  }

  ll ans = 0;
  rep(i, n + 2) rep(j, n + 2) chmax(ans, dp[i][j]);
  cout << ans + add << endl;
  return 0;
}

int main() { /*{{{*/
  solve();
  check_input();
  return 0;
} /*}}}*/


Fixed submission:
#line 2 "header.hpp"

//%snippet.set('header')%
//%snippet.fold()%
#ifndef HEADER_H
#define HEADER_H

// template version 2.0
using namespace std;
#include <bits/stdc++.h>

// varibable settings
const long long INF = 1e18;
template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = (ll)(a); i < (ll)(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _rrep(i, n) rrepi(i, 0, n)
#define rrepi(i, a, b) for (ll i = (ll)((b)-1); i >= (ll)(a); --i)
#define r_rep(...) _overload3(__VA_ARGS__, rrepi, _rrep, )(__VA_ARGS__)
#define each(i, a) for (auto &&i : a)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(...) make_tuple(__VA_ARGS__)
#define ub upper_bound
#define lb lower_bound
#define lpos(A, x) (lower_bound(all(A), x) - A.begin())
#define upos(A, x) (upper_bound(all(A), x) - A.begin())
template <class T> inline void chmax(T &a, const T &b) {
  if ((a) < (b))
    (a) = (b);
}
template <class T> inline void chmin(T &a, const T &b) {
  if ((a) > (b))
    (a) = (b);
}
template <typename X, typename T> auto make_table(X x, T a) {
  return vector<T>(x, a);
}
template <typename X, typename Y, typename Z, typename... Zs>
auto make_table(X x, Y y, Z z, Zs... zs) {
  auto cont = make_table(y, z, zs...);
  return vector<decltype(cont)>(x, cont);
}

#define cdiv(a, b) (((a) + (b)-1) / (b))
#define is_in(x, a, b) ((a) <= (x) && (x) < (b))
#define uni(x)                                                                 \
  sort(all(x));                                                                \
  x.erase(unique(all(x)), x.end())
#define slice(l, r) substr(l, r - l)

typedef long long ll;
typedef long double ld;
using vl = vector<ll>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;

template <typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
void check_input() {
  assert(cin.eof() == 0);
  int tmp;
  cin >> tmp;
  assert(cin.eof() == 1);
}

#if defined(PCM) || defined(LOCAL)
#else
#define dump(...) ;
#define dump_1d(...) ;
#define dump_2d(...) ;
#define cerrendl ;
#endif

#endif /* HEADER_H */
//%snippet.end()%
#line 2 "solve2.cpp"
template <class T = ll> using vec = vector<T>;
struct Fast {
  Fast() {
    std::cin.tie(0);
    ios::sync_with_stdio(false);
  }
} fast;

void recursive_comb(int *indexes, int s, int rest,
                    std::function<void(int *)> f) {
  if (rest == 0) {
    f(indexes);
  } else {
    if (s < 0)
      return;
    recursive_comb(indexes, s - 1, rest, f);
    indexes[rest - 1] = s;
    recursive_comb(indexes, s - 1, rest - 1, f);
  }
}

// nCkの組み合わせに対して処理を実行する
void foreach_comb(int n, int k, std::function<void(int *)> f) {
  int indexes[k];
  recursive_comb(indexes, n - 1, k, f);
}

int solve() {
  ll n;
  cin >> n;
  vector<ll> a(3 * n);
  rep(i, 3 * n) {
    cin >> a[i];
    a[i]--;
  }
  dump(a);
  a.pb(n);
  a.pb(n + 1);

  vec<vec<ll>> dp = make_table(n + 2, n + 2, -INF);
  dp[a[0]][a[1]] = 0;
  dp[a[1]][a[0]] = 0;
  ll now = 2;

  vec<ll> buf(3);
  ll add = 0;
  vec<tuple<ll, ll, ll>> updates;
  vec<ll> local(n + 2, -INF);
  local[a[0]] = 0;
  local[a[1]] = 0;
  while (true) {
    cerrendl;
    dump(now);
    buf[0] = a[now];
    buf[1] = a[now + 1];
    buf[2] = a[now + 2];
    sort(all(buf));
    updates.clear();

    ll mv = *max_element(all(local));

    if (buf[0] == buf[2]) {
      add++;
    } else {
      if (buf[0] == buf[1]) {
        ll p = buf[0];
        ll q = buf[2];
        rep(x, n) updates.pb(mt(q, x, dp[p][x] + 1));
      } else if (buf[1] == buf[2]) {
        ll p = buf[1];
        ll q = buf[0];
        rep(x, n) updates.pb(mt(q, x, dp[p][x] + 1));
      }
      ll p = buf[0];
      ll q = buf[1];
      ll r = buf[2];
      updates.pb(mt(q, r, dp[p][p] + 1));
      updates.pb(mt(p, r, dp[q][q] + 1));
      updates.pb(mt(p, q, dp[r][r] + 1));

      // (2, 1)
      updates.pb(mt(p, q, mv));
      updates.pb(mt(p, r, mv));
      updates.pb(mt(r, q, mv));

      // (1, 2)
      rep(x, n) {
        updates.pb(mt(x, p, local[x]));
        updates.pb(mt(x, q, local[x]));
        updates.pb(mt(x, r, local[x]));
      }
    }

    dump(updates);
    for (auto [x, y, v] : updates) {
      chmax(dp[x][y], v);
      chmax(dp[y][x], v);
      chmax(local[x], v);
      chmax(local[y], v);
    }

    if (now == 3 * n - 1)
      break;
    now += 3;
  }

  ll ans = 0;
  rep(i, n + 2) rep(j, n + 2) chmax(ans, dp[i][j]);
  cout << ans + add << endl;
  return 0;
}

int main() { /*{{{*/
  solve();
  check_input();
  return 0;
} /*}}}*/