Problem p01407 (C++)

Buggy submission (status: Time Limit Exceeded):
#include "bits/stdc++.h"
#include <unordered_map>
#include <unordered_set>
#pragma warning(disable : 4996)
using namespace std;

typedef int Weight;
struct Edge {
  int dest;
  int cap, rev;
  Weight weight;
  bool operator<(const Edge &rhs) const { return weight > rhs.weight; }
};

const int V = 6010;
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;
Weight h[V];            //??????????????£???
Weight dist[V];         //???????????¢
int prevv[V], preve[V]; //??´???????????¨??????

void add_edge(Graph &g, int src, int dest, int cap, Weight weight) {
  g[src].push_back(Edge{dest, cap, (int)g[dest].size(), weight});
  g[dest].push_back(Edge{src, 0, (int)g[src].size() - 1, -weight});
}
#define REP(i, n) for (int i = 0; i < (int)n; ++i)
#define FOR(i, c) for (auto i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
const Weight INF = 1e9;
const Weight ZERO = 0;
//????????????double?????????eps?????????
Weight min_cost_flow(Graph &g, int s, int t, int f) {
  Weight res = ZERO;
  memset(h, ZERO, sizeof(h));
  typedef pair<Weight, int> P;
  REP(i, g.size() / 2 - 1) {
    int v = i + 1;
    REP(j, g[v].size()) {
      Edge &e = g[v][j];
      if (e.cap == 0)
        continue;
      int u = e.dest;
      h[u] = min(h[u], h[v] + e.weight);
    }
    v = i + g.size() / 2 + 1;
    REP(j, g[v].size()) {
      Edge &e = g[v][j];
      if (e.cap == 0)
        continue;
      int u = e.dest;
      h[u] = min(h[u], h[v] + e.weight);
    }
  }
  while (f > 0) {
    priority_queue<P, vector<P>, greater<P>> que;
    fill(dist, dist + V, INF);
    dist[s] = 0;
    que.push(P(ZERO, s));
    while (!que.empty()) {
      P p = que.top();
      que.pop();
      const int v = p.second;
      if (dist[v] < p.first)
        continue;
      REP(i, g[v].size()) {
        Edge &e = g[v][i];
        if (e.cap > 0 && dist[e.dest] > dist[v] + e.weight + h[v] - h[e.dest]) {
          dist[e.dest] = dist[v] + e.weight + h[v] - h[e.dest];
          prevv[e.dest] = v;
          preve[e.dest] = i;
          que.push(P(dist[e.dest], e.dest));
        }
      }
    }
    if (dist[t] == INF)
      return -1;
    REP(v, V) h[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 = 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;
  int V, Xl, Xr;
  cin >> N >> V >> Xl >> Xr;
  struct mogu {
    int x;
    long long int t;
    long long int p;
  };
  vector<mogu> mogus;
  mogus.push_back(mogu{Xl, 0, 0});
  mogus.push_back(mogu{Xr, 0, 0});
  for (int i = 0; i < N; ++i) {
    int x, t, p;
    cin >> x >> t >> p;
    mogus.push_back(mogu{x, t, p});
  }
  sort(mogus.begin(), mogus.end(),
       [](const mogu &l, const mogu &r) { return l.t < r.t; });

  const int start = 0;
  const int mo_in = start + 1;
  const int mo_out = mo_in + N + 2;
  const int goal = mo_out + N + 2;
  Graph g(goal + 1);
  add_edge(g, start, mo_in + 1, 1, 0);
  add_edge(g, start, mo_in + 0, 1, 0);
  for (int i = 0; i < N + 2; ++i) {
    add_edge(g, mo_in + i, mo_out + i, 1, 0);
    for (int j = i + 1; j < N + 2; ++j) {
      const auto amogu(mogus[i]);
      const auto bmogu(mogus[j]);
      {
        long long int time = bmogu.t - amogu.t;
        if (time * V >= abs(bmogu.x - amogu.x)) {
          add_edge(g, mo_out + i, mo_in + j, 1, -bmogu.p);
        }
      }
    }
    add_edge(g, mo_out + i, goal, 1, 0);
  }
  Weight ans = min_cost_flow(g, start, goal, 2);
  cout << -ans << endl;
  return 0;
}

Fixed submission:
#include "bits/stdc++.h"
#include <unordered_map>
#include <unordered_set>
#pragma warning(disable : 4996)
using namespace std;

typedef int Weight;
struct Edge {
  int dest;
  int cap, rev;
  Weight weight;
  bool operator<(const Edge &rhs) const { return weight > rhs.weight; }
};

const int V = 6010;
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;
Weight h[V];            //??????????????£???
Weight dist[V];         //???????????¢
int prevv[V], preve[V]; //??´???????????¨??????

void add_edge(Graph &g, int src, int dest, int cap, Weight weight) {
  g[src].push_back(Edge{dest, cap, (int)g[dest].size(), weight});
  g[dest].push_back(Edge{src, 0, (int)g[src].size() - 1, -weight});
}
#define REP(i, n) for (int i = 0; i < (int)n; ++i)
#define FOR(i, c) for (auto i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
const Weight INF = 1e9;
const Weight ZERO = 0;
//????????????double?????????eps?????????
Weight min_cost_flow(Graph &g, int s, int t, int f) {
  Weight res = ZERO;
  memset(h, ZERO, sizeof(h));
  typedef pair<Weight, int> P;
  REP(i, g.size() / 2 - 1) {
    int v = i + 2;
    REP(j, g[v].size()) {
      Edge &e = g[v][j];
      if (e.cap == 0)
        continue;
      int u = e.dest;
      h[u] = min(h[u], h[v] + e.weight);
    }
    v = i + g.size() / 2 + 1;
    REP(j, g[v].size()) {
      Edge &e = g[v][j];
      if (e.cap == 0)
        continue;
      int u = e.dest;
      h[u] = min(h[u], h[v] + e.weight);
    }
  }
  while (f > 0) {
    priority_queue<P, vector<P>, greater<P>> que;
    fill(dist, dist + V, INF);
    dist[s] = 0;
    que.push(P(ZERO, s));
    while (!que.empty()) {
      P p = que.top();
      que.pop();
      const int v = p.second;
      if (dist[v] < p.first)
        continue;
      REP(i, g[v].size()) {
        Edge &e = g[v][i];
        if (e.cap > 0 && dist[e.dest] > dist[v] + e.weight + h[v] - h[e.dest]) {
          dist[e.dest] = dist[v] + e.weight + h[v] - h[e.dest];
          prevv[e.dest] = v;
          preve[e.dest] = i;
          que.push(P(dist[e.dest], e.dest));
        }
      }
    }
    if (dist[t] == INF)
      return -1;
    REP(v, V) h[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 = 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;
  int V, Xl, Xr;
  cin >> N >> V >> Xl >> Xr;
  struct mogu {
    int x;
    long long int t;
    long long int p;
  };
  vector<mogu> mogus;
  mogus.push_back(mogu{Xl, 0, 0});
  mogus.push_back(mogu{Xr, 0, 0});
  for (int i = 0; i < N; ++i) {
    int x, t, p;
    cin >> x >> t >> p;
    mogus.push_back(mogu{x, t, p});
  }
  sort(mogus.begin(), mogus.end(),
       [](const mogu &l, const mogu &r) { return l.t < r.t; });

  const int start = 0;
  const int mo_in = start + 1;
  const int mo_out = mo_in + N + 2;
  const int goal = mo_out + N + 2;
  Graph g(goal + 1);
  add_edge(g, start, mo_in + 1, 1, 0);
  add_edge(g, start, mo_in + 0, 1, 0);
  for (int i = 0; i < N + 2; ++i) {
    add_edge(g, mo_in + i, mo_out + i, 1, 0);
    for (int j = i + 1; j < N + 2; ++j) {
      const auto amogu(mogus[i]);
      const auto bmogu(mogus[j]);
      {
        long long int time = bmogu.t - amogu.t;
        if (time * V >= abs(bmogu.x - amogu.x)) {
          add_edge(g, mo_out + i, mo_in + j, 1, -bmogu.p);
        }
      }
    }
    add_edge(g, mo_out + i, goal, 1, 0);
  }
  Weight ans = min_cost_flow(g, start, goal, 2);
  cout << -ans << endl;
  return 0;
}