Problem p02361 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
#define SIZE 300005
#define MOD 1000000007LL
#define EPS 1e-10
#define INF 1 << 30
#define LLINF 1LL << 60
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, a, b) for (int i = a; i <= b; i++)
#define DOWN(i, b, a) for (int i = b; i >= a; i--)
#define SET(a, c) memset(a, c, sizeof a)
#define BIT(i, j) ((i) >> (j)) & 1
#define ALL(o) (o).begin(), (o).end()
#define ERASE(o) (o).erase(unique((o).begin(), (o).end()), (o).end())
#define SQ(x) ((x) * (x))
using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pll;
typedef pair<int, int> Pii;
typedef pair<double, double> Pdd;
typedef complex<double> dcomplex;
template <typename T> inline void priv(vector<T> a) {
  REP(i, a.size()) { cerr << a[i] << ((i == a.size() - 1) ? "\\n" : " "); }
}
ll gcd(ll a, ll b) {
  int c = max(a, b);
  int d = min(a, b);
  return c == 0 || d == 0 ? c : gcd(c % d, d);
}
ll lcm(ll a, ll b) { return a == 0 || b == 0 ? 0 : a * b / gcd(a, b); }
ll fact(ll a) {
  ll b = 1;
  FOR(i, 1, a) b *= i;
  return b;
}
ll power(ll x, ll n) {
  ll a = 1;
  REP(i, n) a *= x;
  return a;
}

template <typename T> struct Edge {
  int src, dst;
  T w;
  Edge(){};
  Edge(int src, int dst) : src(src), dst(dst) { w = 1; }
  Edge(int src, int dst, T w) : src(src), dst(dst), w(w) {}
  bool operator<(const Edge &e) const {
    return w != e.w ? w > e.w : dst < e.dst;
  }
  bool operator==(const Edge &e) { return dst == e.dst; }
};

template <typename T> class Graph : public vector<vector<Edge<T>>> {
private:
  pair<T, int> visit(int p, int v) {
    pair<T, int> r(0, v);
    for (auto e : (*this)[v])
      if (e.dst != p) {
        auto t = visit(v, e.dst);
        t.first += e.w;
        if (t.first > r.first)
          r = t;
      }
    return r;
  }

public:
  Graph(int n) { (*this).resize(n); }
  void direct(int s, int t) { (*this)[s].push_back(Edge<T>(s, t)); }
  void direct(int s, int t, T w) { (*this)[s].push_back(Edge<T>(s, t, w)); }
  void undirect(int s, int t) {
    direct(s, t);
    direct(t, s);
  }
  void undirect(int s, int t, T w) {
    direct(s, t, w);
    direct(t, s, w);
  }
  /*
    O(n)
  */
  T diameter(void) {
    auto r = visit(-1, 0);
    auto t = visit(-1, r.second);
    return t.first;
  }

  /*
    s : start point
    O((n+m)log(n))
  */
  vector<T> dijkstra(int s) {
    int n = (*this).size();
    priority_queue<Edge<T>> PQ;
    vector<T> dist(n, INF);
    dist[s] = 0;
    Edge<T> e(-1, s, 0);
    PQ.push(e);
    while (!PQ.empty()) {
      auto f = PQ.top();
      PQ.pop();
      int u = f.dst;
      if (dist[u] < f.w * (-1))
        continue;
      REP(j, (*this)[u].size()) {
        int v = (*this)[u][j].dst;
        if (dist[v] > dist[u] + (*this)[u][j].w) {
          dist[v] = dist[u] + (*this)[u][j].w;
          Edge<T> e(-1, v, dist[v] * (-1));
          PQ.push(e);
        }
      }
    }
    return dist;
  }

  vector<T> bellmanFord(int s) {
    int n = (*this).size();
    vector<T> dist(n, INF);
    dist[s] = 0;
    REP(i, n) {
      bool update = false;
      REP(v, n) for (auto e : (*this)[v]) {
        if (dist[v] != INF && dist[e.dst] > dist[v] + e.w) {
          dist[e.dst] = dist[v] + e.w;
          update = true;
        }
      }
      if (!update)
        break;
    }
    return dist;
  }
};

int main() {
  int v, e, r;
  cin >> v >> e >> r;
  Graph<ll> g(v);
  REP(i, e) {
    int s, t, w;
    cin >> s >> t >> w;
    g.direct(s, t, w);
  }
  auto ans = g.bellmanFord(r);
  for (auto x : ans) {
    if (x == INF)
      cout << "INF" << endl;
    else
      cout << x << endl;
  }
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#define SIZE 300005
#define MOD 1000000007LL
#define EPS 1e-10
#define INF 1 << 29
#define LLINF 1LL << 60
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, a, b) for (int i = a; i <= b; i++)
#define DOWN(i, b, a) for (int i = b; i >= a; i--)
#define SET(a, c) memset(a, c, sizeof a)
#define BIT(i, j) ((i) >> (j)) & 1
#define ALL(o) (o).begin(), (o).end()
#define ERASE(o) (o).erase(unique((o).begin(), (o).end()), (o).end())
#define SQ(x) ((x) * (x))
using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pll;
typedef pair<int, int> Pii;
typedef pair<double, double> Pdd;
typedef complex<double> dcomplex;
template <typename T> inline void priv(vector<T> a) {
  REP(i, a.size()) { cerr << a[i] << ((i == a.size() - 1) ? "\\n" : " "); }
}
ll gcd(ll a, ll b) {
  int c = max(a, b);
  int d = min(a, b);
  return c == 0 || d == 0 ? c : gcd(c % d, d);
}
ll lcm(ll a, ll b) { return a == 0 || b == 0 ? 0 : a * b / gcd(a, b); }
ll fact(ll a) {
  ll b = 1;
  FOR(i, 1, a) b *= i;
  return b;
}
ll power(ll x, ll n) {
  ll a = 1;
  REP(i, n) a *= x;
  return a;
}

template <typename T> struct Edge {
  int src, dst;
  T w;
  Edge(){};
  Edge(int src, int dst) : src(src), dst(dst) { w = 1; }
  Edge(int src, int dst, T w) : src(src), dst(dst), w(w) {}
  bool operator<(const Edge &e) const {
    return w != e.w ? w > e.w : dst < e.dst;
  }
  bool operator==(const Edge &e) { return dst == e.dst; }
};

template <typename T> class Graph : public vector<vector<Edge<T>>> {
private:
  pair<T, int> visit(int p, int v) {
    pair<T, int> r(0, v);
    for (auto e : (*this)[v])
      if (e.dst != p) {
        auto t = visit(v, e.dst);
        t.first += e.w;
        if (t.first > r.first)
          r = t;
      }
    return r;
  }

public:
  Graph(int n) { (*this).resize(n); }
  void direct(int s, int t) { (*this)[s].push_back(Edge<T>(s, t)); }
  void direct(int s, int t, T w) { (*this)[s].push_back(Edge<T>(s, t, w)); }
  void undirect(int s, int t) {
    direct(s, t);
    direct(t, s);
  }
  void undirect(int s, int t, T w) {
    direct(s, t, w);
    direct(t, s, w);
  }
  /*
    O(n)
  */
  T diameter(void) {
    auto r = visit(-1, 0);
    auto t = visit(-1, r.second);
    return t.first;
  }

  /*
    s : start point
    O((n+m)log(n))
  */
  vector<T> dijkstra(int s) {
    int n = (*this).size();
    priority_queue<Edge<T>> PQ;
    vector<T> dist(n, INF);
    dist[s] = 0;
    Edge<T> e(-1, s, 0);
    PQ.push(e);
    while (!PQ.empty()) {
      auto f = PQ.top();
      PQ.pop();
      int u = f.dst;
      if (dist[u] < f.w * (-1))
        continue;
      REP(j, (*this)[u].size()) {
        int v = (*this)[u][j].dst;
        if (dist[v] > dist[u] + (*this)[u][j].w) {
          dist[v] = dist[u] + (*this)[u][j].w;
          Edge<T> e(-1, v, dist[v] * (-1));
          PQ.push(e);
        }
      }
    }
    return dist;
  }
};

int main() {
  int v, e, r;
  cin >> v >> e >> r;
  Graph<ll> g(v);
  REP(i, e) {
    int s, t, w;
    cin >> s >> t >> w;
    g.direct(s, t, w);
  }
  auto ans = g.dijkstra(r);
  for (auto x : ans) {
    if (x == INF)
      cout << "INF" << endl;
    else
      cout << x << endl;
  }
  return 0;
}