Problem p00719 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll = long long;
using vi = vector<int>;
using vl = vector<long long>;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
#define ITR(i, c) for (auto i = begin(c); i != end(c); ++i)
#define FORE(x, c) for (auto &x : c)
#define REPF(i, a, n) for (int i = a, i##_len = (int)(n); i < i##_len; ++i)
#define REP(i, n) REPF(i, 0, n)
#define REPR(i, n) for (int i = (int)(n); i >= 0; --i)
#define REPW(i, n) for (i = 0; i < (int)(n); ++i)
#define ALL(c) begin(c), end(c)
#define RALL(c) rbegin(c), rend(c) // c++14
#define SZ(c) ((int)c.size())
#define EXIST(c, x) (c.find(x) != end(c))
#define OUTOFRANGE(y, x, h, w) (y < 0 || x < 0 || y >= h || x >= w)
#define dump(...)
const int DX[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0},
          DY[9] = {-1, 0, 1, 0, -1, 1, 1, -1, 0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  ITR(i, v) os << *i << (i == end(v) - 1 ? "" : "\\n");
  return os;
}
template <class T> istream &operator>>(istream &is, vector<T> &v) {
  ITR(i, v) is >> *i;
  return is;
}
template <class T> istream &operator>>(istream &is, pair<T, T> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
//------------------------------------------------------------------------------
struct before_main_function {
  before_main_function() {
#ifdef int
#undef INF
#define INF INFLL
#define stoi stoll
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << setprecision(15) << fixed;
  }
} before_main_function;
//------------------------------------------------------------------------------

signed main() {
  while (1) {
    int n, m, p, a, b;
    cin >> n >> m >> p >> a >> b;
    if (n + m + p + a + b == 0)
      break;
    a--;
    b--;
    vector<double> ticket(n);
    cin >> ticket;
    vector<vector<double>> d(m, vector<double>(m, INF));
    REP(i, p) {
      int x, y, z;
      cin >> x >> y >> z;
      x--, y--;
      d[x][y] = d[y][x] = z;
    }
    vector<vector<double>> dp((1 << n), vector<double>(m, INF));
    dp[(1 << n) - 1][a] = 0;
    for (int i = (1 << n) - 1; i >= 0; --i) {
      REP(j, m) {
        if (dp[i][j] != INF) {
          REP(k, m) {
            if (d[j][k] != INF) {
              REP(l, n) {
                if (i & (1 << l)) {
                  chmin(dp[i & (~(1 << l))][k],
                        dp[i][j] + (d[j][k] / ticket[l]));
                }
              }
            }
          }
        }
      }
    }
    double ans = INF;
    REP(i, 1 << n) { chmin(ans, dp[i][b]); }
    if (ans == INF) {
      cout << "Impossible" << endl;
    } else {
      cout << ans << endl;
    }
  }
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll = long long;
using vi = vector<int>;
using vl = vector<long long>;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
#define ITR(i, c) for (auto i = begin(c); i != end(c); ++i)
#define FORE(x, c) for (auto &x : c)
#define REPF(i, a, n) for (int i = a, i##_len = (int)(n); i < i##_len; ++i)
#define REP(i, n) REPF(i, 0, n)
#define REPR(i, n) for (int i = (int)(n); i >= 0; --i)
#define REPW(i, n) for (i = 0; i < (int)(n); ++i)
#define ALL(c) begin(c), end(c)
#define RALL(c) rbegin(c), rend(c) // c++14
#define SZ(c) ((int)c.size())
#define EXIST(c, x) (c.find(x) != end(c))
#define OUTOFRANGE(y, x, h, w) (y < 0 || x < 0 || y >= h || x >= w)
#define dump(...)
const int DX[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0},
          DY[9] = {-1, 0, 1, 0, -1, 1, 1, -1, 0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  ITR(i, v) os << *i << (i == end(v) - 1 ? "" : "\\n");
  return os;
}
template <class T> istream &operator>>(istream &is, vector<T> &v) {
  ITR(i, v) is >> *i;
  return is;
}
template <class T> istream &operator>>(istream &is, pair<T, T> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
//------------------------------------------------------------------------------
struct before_main_function {
  before_main_function() {
#ifdef int
#undef INF
#define INF INFLL
#define stoi stoll
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << setprecision(15) << fixed;
  }
} before_main_function;
//------------------------------------------------------------------------------

signed main() {
  while (1) {
    int n, m, p, a, b;
    cin >> n >> m >> p >> a >> b;
    if (n + m + p + a + b == 0)
      break;
    a--;
    b--;
    vector<double> ticket(n);
    cin >> ticket;
    vector<unordered_map<int, vector<pair<int, double>>>> g(m);
    REP(i, p) {
      double x, y, z;
      cin >> x >> y >> z;
      x--, y--;
      REP(j, n) g[x][j].push_back({y, z / ticket[j]});
      REP(j, n) g[y][j].push_back({x, z / ticket[j]});
    }
    vector<bool> vis(m, false);
    double ans = INF;
    function<void(int, double, int)> dfs = [&](int i, double d, int s) {
      if (i == b) {
        chmin(ans, d);
      }
      REP(j, n) {
        if (!(s & (1 << j))) {
          FORE(e, g[i][j]) {
            if (vis[e.first])
              continue;
            vis[e.first] = true;
            dfs(e.first, d + e.second, s | (1 << j));
            vis[e.first] = false;
          }
        }
      }
    };
    vis[a] = true;
    dfs(a, 0, 0);
    cout << (ans == INF ? "Impossible" : to_string(ans)) << endl;
  }
  return 0;
}