Problem p00117 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <queue>
#include <vector>
using namespace std;

#define REP(i, n) for (int i = 0; i < (int)n; ++i)
#define FOR(i, c)                                                              \
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define INF 1 << 30

typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) : src(src), dst(dst), weight(weight) {}
};

bool operator<(const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
             e.src != f.src ? e.src < f.src
                            : e.dst < f.dst;
}

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void shortestPath(const Graph &g, int s, vector<Weight> &dist) {
  int n = g.size();
  dist.assign(n, INF);
  dist[s] = 0;
  priority_queue<Edge> Q; // "e < f" <=> "e.weight > f.weight"
  for (Q.push(Edge(-2, s, 0)); !Q.empty();) {
    Edge e = Q.top();
    Q.pop();
    if (dist[e.dst] < e.weight)
      continue;
    FOR(f, g[e.dst]) {
      if (dist[f->dst] > e.weight + f->weight) {
        dist[f->dst] = e.weight + f->weight;
        Q.push(Edge(f->src, f->dst, e.weight + f->weight));
      }
    }
  }
}

int main() {
  int n, m;
  cin >> n >> m;
  Graph g(n);
  REP(i, m) {
    int a, b, c, d;
    scanf("%d,%d,%d,%d\n", &a, &b, &c, &d);
    a--;
    b--;
    g[a].push_back(Edge(a, b, c));
    g[b].push_back(Edge(b, a, d));
  }
  int s, d, y1, y2;
  scanf("%d,%d,%d,%d\n", &s, &d, &y1, &y2);
  s--;
  d--;
  vector<int> dist;
  int hoge;
  shortestPath(g, s, dist);
  hoge = dist[d];
  shortestPath(g, dist[d], dist);
  hoge += dist[s];
  cout << y1 - y2 - hoge << endl;
}

Fixed submission:
#include <algorithm>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <queue>
#include <vector>
using namespace std;

#define REP(i, n) for (int i = 0; i < (int)n; ++i)
#define FOR(i, c)                                                              \
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define INF 1 << 30

typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) : src(src), dst(dst), weight(weight) {}
};

bool operator<(const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
             e.src != f.src ? e.src < f.src
                            : e.dst < f.dst;
}

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void shortestPath(const Graph &g, int s, vector<Weight> &dist) {
  int n = g.size();
  dist.assign(n, INF);
  dist[s] = 0;
  priority_queue<Edge> Q; // "e < f" <=> "e.weight > f.weight"
  for (Q.push(Edge(-2, s, 0)); !Q.empty();) {
    Edge e = Q.top();
    Q.pop();
    if (dist[e.dst] < e.weight)
      continue;
    FOR(f, g[e.dst]) {
      if (dist[f->dst] > e.weight + f->weight) {
        dist[f->dst] = e.weight + f->weight;
        Q.push(Edge(f->src, f->dst, e.weight + f->weight));
      }
    }
  }
}

int main() {
  int n, m;
  cin >> n >> m;
  Graph g(n);
  REP(i, m) {
    int a, b, c, d;
    scanf("%d,%d,%d,%d\n", &a, &b, &c, &d);
    a--;
    b--;
    g[a].push_back(Edge(a, b, c));
    g[b].push_back(Edge(b, a, d));
  }
  int s, d, y1, y2;
  scanf("%d,%d,%d,%d\n", &s, &d, &y1, &y2);
  s--;
  d--;
  vector<int> dist;
  int hoge;
  shortestPath(g, s, dist);
  hoge = dist[d];
  shortestPath(g, d, dist);
  hoge += dist[s];
  cout << y1 - y2 - hoge << endl;
}