Problem p01732 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>
#include <unordered_map>
using namespace std;
#define INF 99999999

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 unordered_map<int, Edges> Graph;

void shortestPath(Graph &g, int s, unordered_map<int, Weight> &dist,
                  unordered_map<int, int> &prev) {
  for (auto &f : g)
    dist[f.first] = 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 (prev.find(e.dst) != prev.end())
      continue;
    prev[e.dst] = e.src;
    for (auto &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));
      }
    }
  }
}

char buf[1001];
int W;
int coor(int x, int y) { return (y) * (W * 2 + 2) + x; }
int main() {
  int H, N, X1, Y1, X2, Y2;
  scanf("%d%d%d%d%d%d%d", &W, &H, &N, &X1, &Y1, &X2, &Y2);
  X1 = coor(X1 * 2, Y1 * 2), X2 = coor(X2 * 2, Y2 * 2);
  vector<vector<int>> m(H * 2 + 1);
  for (auto &&e : m)
    e.resize(W * 2 + 1);
  for (int i = 0; i < N; i++) {
    int x, y, t, l;
    scanf("%d%d%d%s", &x, &y, &t, buf);
    l = strlen(buf);
    x = 2 * x + 1, y = 2 * y + 1;
    for (int j = 0; j < t; j++) {
      for (int k = 0; k < l; k++) {
        int c = buf[k];
        if (c == 'L' && 1 < x)
          m[y][x - 1]++, x -= 2;
        if (c == 'U' && 1 < y)
          m[y - 1][x]++, y -= 2;
        if (c == 'R' && x < W * 2 - 1)
          m[y][x + 1]++, x += 2;
        if (c == 'D' && y < H * 2 - 1)
          m[y + 1][x]++, y += 2;
      }
    }
  }
  Graph g;
  for (int h = 0; h <= H * 2; h += 2)
    for (int w = 0; w <= W * 2; w += 2) {
      int a = coor(w, h), b;
      if (h < H * 2 - 1)
        b = coor(w, h + 2), g[a].push_back(Edge(a, b, m[h + 1][w])),
        g[b].push_back(Edge(b, a, m[h + 1][w]));
      if (w < W * 2 - 1)
        b = coor(w + 2, h), g[a].push_back(Edge(a, b, m[h][w + 1])),
        g[b].push_back(Edge(b, a, m[h][w + 1]));
    }
  unordered_map<int, Weight> dist;
  unordered_map<int, int> prev;
  shortestPath(g, X1, dist, prev);
  printf("%d\\n", dist[X2]);
}

Error: 0

Fixed submission:

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>
#include <unordered_map>
using namespace std;
#define INF 99999999

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 unordered_map<int, Edges> Graph;

void shortestPath(Graph &g, int s, unordered_map<int, Weight> &dist,
                  unordered_map<int, int> &prev) {
  for (auto &f : g)
    dist[f.first] = 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 (prev.find(e.dst) != prev.end())
      continue;
    prev[e.dst] = e.src;
    for (auto &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));
      }
    }
  }
}

char buf[101];
int W;
int coor(int x, int y) { return (y) * (W * 2 + 2) + x; }
int main() {
  int H, N, X1, Y1, X2, Y2;
  scanf("%d%d%d%d%d%d%d", &W, &H, &N, &X1, &Y1, &X2, &Y2);
  X1 = coor(X1 * 2, Y1 * 2), X2 = coor(X2 * 2, Y2 * 2);
  vector<vector<int>> m(H * 2 + 1);
  for (auto &&e : m)
    e.resize(W * 2 + 1);
  for (int i = 0; i < N; i++) {
    int x, y, t, l;
    scanf("%d%d%d%s", &x, &y, &t, buf);
    l = strlen(buf);
    x = 2 * x + 1, y = 2 * y + 1;
    for (int j = 0; j < t; j++) {
      for (int k = 0; k < l; k++) {
        int c = buf[k];
        if (c == 'L' && 1 < x)
          m[y][x - 1]++, x -= 2;
        if (c == 'U' && 1 < y)
          m[y - 1][x]++, y -= 2;
        if (c == 'R' && x < W * 2 - 1)
          m[y][x + 1]++, x += 2;
        if (c == 'D' && y < H * 2 - 1)
          m[y + 1][x]++, y += 2;
      }
    }
  }
  Graph g;
  for (int h = 0; h <= H * 2; h += 2)
    for (int w = 0; w <= W * 2; w += 2) {
      int a = coor(w, h), b;
      if (h < H * 2 - 1)
        b = coor(w, h + 2), g[a].push_back(Edge(a, b, m[h + 1][w])),
        g[b].push_back(Edge(b, a, m[h + 1][w]));
      if (w < W * 2 - 1)
        b = coor(w + 2, h), g[a].push_back(Edge(a, b, m[h][w + 1])),
        g[b].push_back(Edge(b, a, m[h][w + 1]));
    }
  unordered_map<int, Weight> dist;
  unordered_map<int, int> prev;
  shortestPath(g, X1, dist, prev);
  printf("%d\\n", dist[X2]);
}