Problem p01151 (C++) — buggy submission, verdict: Memory Limit Exceeded

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(c) (c).begin(), (c).end()
#define pb push_back
#define dbg(...)                                                               \\
  do {                                                                         \\
    cerr << __LINE__ << ": ";                                                  \\
    dbgprint(#__VA_ARGS__, __VA_ARGS__);                                       \\
  } while (0);

using namespace std;

namespace std {
template <class S, class T> struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T> struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v)
      h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
} // namespace std
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  rep(i, v.size()) os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v)
    os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v)
    os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;

vi ans, cur;
unordered_set<vi> vis;
bool solve(vi v, int sum) {
  if (vis.count(v))
    return 0;
  vis.insert(v);

  if (v.empty()) {
    ans = cur;
    reverse(all(ans));
    return 1;
  }
  rep(i,
      v.size()) if (i == 0 || v[i] != v[i - 1]) if ((sum - v[i]) % v[i] == 0) {
    cur.pb(v[i]);
    vi next = v;
    next.erase(next.begin() + i);
    if (solve(next, sum - v[i]))
      return 1;
    cur.pop_back();
  }
  return 0;
}

int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int n;
  while (cin >> n, n) {
    vi v(n);
    rep(i, n) cin >> v[i];
    sort(all(v), greater<int>());
    ans.clear();
    cur.clear();
    vis.clear();
    if (!solve(v, accumulate(all(v), 0))) {
      cout << "No" << endl;
    } else {
      rep(i, n) cout << ans[i] << (i == n - 1 ? "\\n" : " ");
    }
  }
  return 0;
}


Error: MLE

Fixed submission:

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(c) (c).begin(), (c).end()
#define pb push_back
#define dbg(...)                                                               \\
  do {                                                                         \\
    cerr << __LINE__ << ": ";                                                  \\
    dbgprint(#__VA_ARGS__, __VA_ARGS__);                                       \\
  } while (0);

using namespace std;

namespace std {
template <class S, class T> struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T> struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v)
      h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
} // namespace std
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  rep(i, v.size()) os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v)
    os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v)
    os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;

vi ans, cur;
unordered_set<vi> vis;
bool solve(vi v, int sum = 0) {
  if (vis.count(v))
    return 0;
  vis.insert(v);

  if (v.empty()) {
    ans = cur;
    return 1;
  }
  rep(i, v.size()) if (i == 0 || v[i] != v[i - 1]) if (sum % v[i] == 0) {
    cur.pb(v[i]);
    vi next = v;
    next.erase(next.begin() + i);
    if (solve(next, sum + v[i]))
      return 1;
    cur.pop_back();
  }
  return 0;
}

int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int n;
  while (cin >> n, n) {
    vi v(n);
    rep(i, n) cin >> v[i];
    sort(all(v), greater<int>());
    ans.clear();
    cur.clear();
    vis.clear();
    if (!solve(v)) {
      cout << "No" << endl;
    } else {
      rep(i, n) cout << ans[i] << (i == n - 1 ? "\\n" : " ");
    }
  }
  return 0;
}