Problem p02542 (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
// #dLefine 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
#ifdef HK_CUP
  freopen("finput.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif

  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
#ifndef HK_CUP
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
#endif
  return 0;
}

const ll oo = 1e12 + 10;

template <int N> struct Mcmf {
  struct edge {
    int from, to, flow, cap, cost;
  };
  vector<edge> e;
  vi g[N];

  inline void add_edge(int from, int to, int cap, int cost) {
    //        cout << from << " , " << to << " = (" << cap << ", " << cost <<
    //        ")" << endl;
    g[from].push_back(e.size());
    e.push_back({from, to, 0, cap, cost});
    g[to].push_back(e.size());
    e.push_back({to, from, 0, 0, -cost});
  }

  int d[N];
  bool in_que[N];
  int from[N];

  pii mcmf(int s, int t) {
    int flow = 0, cost = 0;
    while (1) {
      fill(d, d + t + 1, oo);
      fill(in_que, in_que + t + 1, 0);
      d[s] = 0;
      in_que[s] = 1;
      queue<int> q;
      q.push(s);
      while (!q.empty()) {
        int v = q.front();
        q.pop();
        in_que[v] = 0;
        for (int id : g[v]) {
          int to = e[id].to;
          if (e[id].cap > e[id].flow && d[to] > d[v] + e[id].cost) {
            d[to] = d[v] + e[id].cost;
            from[to] = id;
            if (!in_que[to]) {
              q.push(to);
              in_que[to] = 1;
            }
          }
        }
      }
      if (d[t] == oo)
        break;
      int v = t;
      vi ids;
      int pushed = oo;
      while (v != s) {
        int id = from[v];
        ids.push_back(id);
        v = e[id].from;
        inmin(pushed, e[id].cap - e[id].flow);
      }
      flow += pushed;
      for (auto id : ids) {
        e[id].flow += pushed;
        e[id ^ 1].flow -= pushed;
        cost += pushed * e[id].cost;
      }
    }
    return {flow, cost};
  };
};

const int oosmall = 1e6 + 10;
const int N = 55;

string mat[N];

const int S = 1e4 + 10;

void smain() {

  int n, m;
  cin >> n >> m;
  fori(i, n) { cin >> mat[i]; }
  Mcmf<S> mcmf;

  int s = n * m;
  int t = s + 1;
  int cnt0 = 0;
  fori(i, n) {
    fori(j, m) {
      mcmf.add_edge(i * m + j, t, 1, 0);
      if (mat[i][j] == 'o') {
        cnt0++;
        mcmf.add_edge(s, i * m + j, 1, -oosmall);
      }
      if (i + 1 != n && mat[i][j] != '#' && mat[i + 1][j] != '#') {
        mcmf.add_edge(i * m + j, (i + 1) * m + j, oosmall, -1);
      }
      if (j + 1 != m && mat[i][j] != '#' && mat[i][j + 1] != '#') {
        mcmf.add_edge(i * m + j, i * m + j + 1, oosmall, -1);
      }
    }
  }

  pii ans = mcmf.mcmf(s, t);
  watch(ans);
  cout << -(ans.second + oosmall * cnt0);
}

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
// #dLefine 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
#ifdef HK_CUP
  freopen("finput.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif

  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
#ifndef HK_CUP
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
#endif
  return 0;
}

template <class flow_t> struct Hungarian {
  flow_t oo;
  Hungarian(flow_t oo) : oo(oo) {}
  flow_t hungarian(vector<vector<flow_t>> a) { /* 1-INDEXED O(n * n * m) */
    int n = (int)a.size() - 1;
    int m = (int)a[0].size() - 1;
    vector<flow_t> u(n + 1), v(m + 1);
    vector<int> p(m + 1), way(m + 1);
    for (int i = 1; i <= n; ++i) {
      p[0] = i;
      int j0 = 0;
      vector<flow_t> minv(m + 1, oo);
      vector<char> used(m + 1, false);
      do {
        used[j0] = true;
        int i0 = p[j0], j1;
        flow_t delta = oo;
        for (int j = 1; j <= m; ++j)
          if (!used[j]) {
            flow_t cur = a[i0][j] - u[i0] - v[j];
            if (cur < minv[j])
              minv[j] = cur, way[j] = j0;
            if (minv[j] < delta)
              delta = minv[j], j1 = j;
          }
        for (int j = 0; j <= m; ++j)
          if (used[j])
            u[p[j]] += delta, v[j] -= delta;
          else
            minv[j] -= delta;
        j0 = j1;
      } while (p[j0] != 0);
      do {
        int j1 = way[j0];
        p[j0] = p[j1];
        j0 = j1;
      } while (j0);
    }
    vector<int> ans(n + 1);
    for (int j = 1; j <= m; ++j)
      ans[p[j]] = j;
    flow_t total_cost = -v[0];
    return total_cost;
  }
};

const int oo = 1e8 + 10;
const int N = 55;

string mat[N];

void smain() {

  int n, m;
  cin >> n >> m;
  fori(i, n) { cin >> mat[i]; }
  vvi cost(n * m + 1, vi(n * m + 1, 0));
  fori(i, n) {
    fori(j, m) {
      if (mat[i][j] == 'o') {
        vvi used(n, vi(m, false));
        used[i][j] = 1;
        for (int ii = i; ii < n; ++ii) {
          for (int jj = j; jj < m; ++jj) {
            if (used[ii][jj]) {
              if (ii + 1 != n && mat[ii + 1][jj] != '#') {
                used[ii + 1][jj] = 1;
              }
              if (jj + 1 != m && mat[ii][jj + 1] != '#') {
                used[ii][jj + 1] = 1;
              }
            }
          }
        }
        fori(ii, n) {
          fori(jj, m) {
            int cs = oo;
            if (used[ii][jj]) {
              cs = -(abs(ii - i) + abs(jj - j));
            }
            cost[i * m + j + 1][ii * m + jj + 1] = cs;
          }
        }
      }
    }
  }

  //    fori (i, cost.size()) {
  //        fori (j, cost.size()) {
  //            cerr << cost[i][j] << ' ';
  //        }
  //        cerr << '\\n';
  //    }
  Hungarian<int> hungarian(oo);
  int ans = hungarian.hungarian(cost);
  cout << -ans;
}