Problem p00825 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#define r(i, n) for (int i = 0; i < n; i++)
using namespace std;

struct PrimalDual {
  const int INF = 1 << 28;
  typedef pair<int, int> P;
  struct edge {
    int to, cap, cost, rev;
    edge() {}
    edge(int to, int cap, int cost, int rev)
        : to(to), cap(cap), cost(cost), rev(rev) {}
  };

  int n;
  vector<vector<edge>> G;
  vector<int> h, dist, prevv, preve;

  PrimalDual() {}
  PrimalDual(int sz) : n(sz), G(sz), h(sz), dist(sz), prevv(sz), preve(sz) {}

  void add_edge(int from, int to, int cap, int cost) {
    G[from].push_back(edge(to, cap, cost, G[to].size()));
    G[to].push_back(edge(from, 0, -cost, G[from].size() - 1));
  }

  int flow(int s, int t, int f) {
    int res = 0;
    fill(h.begin(), h.end(), 0);
    while (f > 0) {
      priority_queue<P, vector<P>, greater<P>> que;
      fill(dist.begin(), dist.end(), INF);
      dist[s] = 0;
      que.push(P(0, s));
      while (!que.empty()) {
        P p = que.top();
        que.pop();
        int v = p.second;
        if (dist[v] < p.first)
          continue;
        for (int i = 0; i < (int)G[v].size(); i++) {
          edge &e = G[v][i];
          if (e.cap > 0 && dist[e.to] > dist[v] + e.cost + h[v] - h[e.to]) {
            dist[e.to] = dist[v] + e.cost + h[v] - h[e.to];
            prevv[e.to] = v;
            preve[e.to] = i;
            que.push(P(dist[e.to], e.to));
          }
        }
      }
      if (dist[t] == INF)
        return -1;
      for (int v = 0; v < n; v++)
        h[v] += dist[v];
      int d = f;
      for (int v = t; v != s; v = prevv[v]) {
        d = min(d, G[prevv[v]][preve[v]].cap);
      }
      f -= d;
      res += d * h[t];
      for (int v = t; v != s; v = prevv[v]) {
        edge &e = G[prevv[v]][preve[v]];
        e.cap -= d;
        G[v][e.rev].cap += d;
      }
    }
    return res;
  }
};

int main() {
  int n;
  while (cin >> n, n) {
    PrimalDual p(367);
    r(i, n) {
      int a, b, c;
      cin >> a >> b >> c;
      p.add_edge(a, b + 1, 1, -c);
    }
    r(i, 367) p.add_edge(i, i + 1, 2, 0);
    cout << -p.flow(0, 366, 2) << endl;
  }
}


Fixed submission:
#include <bits/stdc++.h>
#define r(i, n) for (int i = 0; i < n; i++)
using namespace std;

struct PrimalDual {
  const int INF = 1 << 28;
  typedef pair<int, int> P;
  struct edge {
    int to, cap, cost, rev;
    edge() {}
    edge(int to, int cap, int cost, int rev)
        : to(to), cap(cap), cost(cost), rev(rev) {}
  };

  int n;
  vector<vector<edge>> G;
  vector<int> h, dist, prevv, preve;

  PrimalDual() {}
  PrimalDual(int sz) : n(sz), G(sz), h(sz), dist(sz), prevv(sz), preve(sz) {}

  void add_edge(int from, int to, int cap, int cost) {
    G[from].push_back(edge(to, cap, cost, G[to].size()));
    G[to].push_back(edge(from, 0, -cost, G[from].size() - 1));
  }

  int flow(int s, int t, int f) {
    int res = 0;
    fill(h.begin(), h.end(), 0);
    while (f > 0) {
      priority_queue<P, vector<P>, greater<P>> que;
      fill(dist.begin(), dist.end(), INF);
      dist[s] = 0;
      que.push(P(0, s));
      while (!que.empty()) {
        P p = que.top();
        que.pop();
        int v = p.second;
        if (dist[v] < p.first)
          continue;
        for (int i = 0; i < (int)G[v].size(); i++) {
          edge &e = G[v][i];
          if (e.cap > 0 && dist[e.to] > dist[v] + e.cost + h[v] - h[e.to]) {
            dist[e.to] = dist[v] + e.cost + h[v] - h[e.to];
            prevv[e.to] = v;
            preve[e.to] = i;
            que.push(P(dist[e.to], e.to));
          }
        }
      }
      if (dist[t] == INF)
        return -1;
      for (int v = 0; v < n; v++)
        h[v] += dist[v];
      int d = f;
      for (int v = t; v != s; v = prevv[v]) {
        d = min(d, G[prevv[v]][preve[v]].cap);
      }
      f -= d;
      res += d * h[t];
      for (int v = t; v != s; v = prevv[v]) {
        edge &e = G[prevv[v]][preve[v]];
        e.cap -= d;
        G[v][e.rev].cap += d;
      }
    }
    return res;
  }
};

int main() {
  int n;
  while (cin >> n, n) {
    PrimalDual p(368);
    r(i, n) {
      int a, b, c;
      cin >> a >> b >> c;
      p.add_edge(a, b + 1, 1, -c);
    }
    r(i, 367) p.add_edge(i, i + 1, 2, 0);
    cout << -p.flow(0, 366, 2) << endl;
  }
}