Problem p00721 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < ((int)b); ++i)
#define RFOR(i, a) for (int i = (a); i >= 0; --i)
#define FOE(i, a) for (auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x) cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v, x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL << (n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template <typename T> using V = std::vector<T>;
template <typename T> using VV = std::vector<std::vector<T>>;
template <typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template <class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template <class T> inline void print(T x) { std::cout << x << std::endl; }
template <class T> inline void print_vec(const std::vector<T> &v) {
  for (int i = 0; i < v.size(); ++i) {
    if (i != 0) {
      std::cout << " ";
    }
    std::cout << v[i];
  }
  std::cout << "\\n";
}
template <class T> inline bool inside(T y, T x, T H, T W) {
  return 0 <= y and y < H and 0 <= x and x < W;
}
template <class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
template <class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) {
  return abs(x1 - x2) + abs(y1 - y2);
}

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = {0, 1, 0, -1},
                       dx4 = {1, 0, -1, 0}; // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = {0, -1, 0, 1, 1, -1, -1, 1},
                       dx8 = {1, 0, -1, 0, 1, 1, -1, -1};

using namespace std;

map<pair<pair<int, int>, pair<int, int>>, LL> memo;
LL dist(pair<int, int> p1, pair<int, int> p2, const vector<string> &f) {
  auto key = make_pair(p1, p2);
  auto key2 = make_pair(p2, p1);
  if (memo.find(key) != memo.end()) {
    return memo[key];
  }
  if (memo.find(key2) != memo.end()) {
    return memo[key2];
  }

  vector<vector<LL>> cost(f.size(), vector<LL>(f[0].size(), INF));
  cost[p1.first][p1.second] = 0;

  queue<pair<int, int>> que;
  que.push(p1);

  while (not que.empty()) {
    int y = que.front().first;
    int x = que.front().second;
    que.pop();

    FOR(i, 0, 4) {
      int ny = dy4[i] + y;
      int nx = dx4[i] + x;

      if (inside(ny, nx, (int)f.size(), (int)f[0].size()) and
          f[ny][nx] != 'x' and cost[ny][nx] > cost[y][x] + 1) {
        cost[ny][nx] = cost[y][x] + 1;
        que.push(make_pair(ny, nx));
      }
    }
  }

  return memo[key] = cost[p2.first][p2.second];
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  while (true) {
    memo.clear();
    int W, H;
    cin >> W >> H;
    if (W == 0 and H == 0) {
      break;
    }

    vector<pair<int, int>> v;
    vector<string> f(H);
    int sy, sx;
    FOR(i, 0, H) {
      cin >> f[i];
      FOR(j, 0, W) {
        if (f[i][j] == 'o') {
          sy = i;
          sx = j;
        }
        if (f[i][j] == '*') {
          v.emplace_back(make_pair(i, j));
        }
      }
    }

    if (v.size() == 0) {
      print(0);
      continue;
    }

    LL ans = INF;
    sort(ALL(v));
    do {
      LL d = dist(make_pair(sy, sx), v[0], f);
      FOR(i, 0, v.size() - 1) { d += dist(v[i], v[i + 1], f); }
      ans = min(ans, d);

    } while (next_permutation(ALL(v)));

    if (ans == INF) {
      print(-1);
    } else {
      print(ans);
    }
  }

  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < ((int)b); ++i)
#define RFOR(i, a) for (int i = (a); i >= 0; --i)
#define FOE(i, a) for (auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x) cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v, x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL << (n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template <typename T> using V = std::vector<T>;
template <typename T> using VV = std::vector<std::vector<T>>;
template <typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template <class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template <class T> inline void print(T x) { std::cout << x << std::endl; }
template <class T> inline void print_vec(const std::vector<T> &v) {
  for (int i = 0; i < v.size(); ++i) {
    if (i != 0) {
      std::cout << " ";
    }
    std::cout << v[i];
  }
  std::cout << "\\n";
}
template <class T> inline bool inside(T y, T x, T H, T W) {
  return 0 <= y and y < H and 0 <= x and x < W;
}
template <class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
template <class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) {
  return abs(x1 - x2) + abs(y1 - y2);
}

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = {0, 1, 0, -1},
                       dx4 = {1, 0, -1, 0}; // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = {0, -1, 0, 1, 1, -1, -1, 1},
                       dx8 = {1, 0, -1, 0, 1, 1, -1, -1};

using namespace std;

LL dist(pair<int, int> p1, pair<int, int> p2, const vector<string> &f) {
  vector<vector<LL>> cost(f.size(), vector<LL>(f[0].size(), INF));
  cost[p1.first][p1.second] = 0;

  queue<pair<int, int>> que;
  que.push(p1);

  while (not que.empty()) {
    int y = que.front().first;
    int x = que.front().second;
    que.pop();

    FOR(i, 0, 4) {
      int ny = dy4[i] + y;
      int nx = dx4[i] + x;

      if (inside(ny, nx, (int)f.size(), (int)f[0].size()) and
          f[ny][nx] != 'x' and cost[ny][nx] > cost[y][x] + 1) {
        cost[ny][nx] = cost[y][x] + 1;
        que.push(make_pair(ny, nx));
      }
    }
  }

  return cost[p2.first][p2.second];
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  while (true) {
    int W, H;
    cin >> W >> H;
    if (W == 0 and H == 0) {
      break;
    }

    vector<pair<int, int>> v;
    vector<string> f(H);
    int sy, sx;
    FOR(i, 0, H) {
      cin >> f[i];
      FOR(j, 0, W) {
        if (f[i][j] == 'o') {
          sy = i;
          sx = j;
        }
        if (f[i][j] == '*') {
          v.emplace_back(make_pair(i, j));
        }
      }
    }

    if (v.size() == 0) {
      print(0);
      continue;
    }

    LL ans = INF;
    sort(ALL(v));
    do {
      LL d = dist(make_pair(sy, sx), v[0], f);
      FOR(i, 0, v.size() - 1) { d += dist(v[i], v[i + 1], f); }
      ans = min(ans, d);

    } while (next_permutation(ALL(v)));

    if (ans == INF) {
      print(-1);
    } else {
      print(ans);
    }
  }

  return 0;
}