Problem p01419 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
// #define LOG(...)
#define FOR(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define REP(i, n) for (int i = 0; i < (int)(n); ++i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())
#define RSORT(c) sort((c).rbegin(), (c).rend())
#define CLR(a) memset((a), 0, sizeof(a))
#define WRAP(x, y, w, h) (0 <= x && x < w && 0 <= y && y < h)

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};

struct UnionFind {
  vector<int> v;
  UnionFind(int n) : v(n) {
    for (int i = 0; i < n; i++)
      v[i] = i;
  }
  int find(int x) { return v[x] == x ? x : v[x] = find(v[x]); }
  void unite(int x, int y) { v[find(x)] = find(y); }
};
pii pre[50][50][50][50];
int main() {
  int h, w, m;
  cin >> h >> w >> m;
  vector<string> cell(h);
  REP(i, h)
  cin >> cell[i];
  vector<vvi> ele(3, vvi(h, vi(w)));
  REP(k, 3)
  REP(i, h)
  REP(j, w)
  cin >> ele[k][i][j];
  vector<pii> task(m);
  REP(i, m)
  cin >> task[i].first >> task[i].second;

  REP(i, h) {
    REP(j, w) {
      if (cell[i][j] == '.') {
        pre[i][j][i][j] = {i, j};
        queue<pair<pii, pii>> Q; // now pre
        Q.push({{i, j}, {i, j}});
        while (!Q.empty()) {
          pair<pii, pii> q = Q.front();
          Q.pop();
          int ny = q.first.first;
          int nx = q.first.second;
          int py = q.second.first;
          int px = q.second.second;
          REP(k, 4) {
            if (nx + dx[k] == px && ny + dy[k] == py)
              continue;
            if (WRAP(nx + dx[k], ny + dy[k], w, h)) {
              if (cell[ny + dy[k]][nx + dx[k]] == '.') {
                pre[i][j][ny + dy[k]][nx + dx[k]] = {ny, nx};
                Q.push({{ny + dy[k], nx + dx[k]}, {ny, nx}});
              }
            }
          }
        }
      }
    }
  }
  int time = 0;
  int idx = 0;
  pii now = task[0];
  vector<vvi> used(h, vvi(w));
  while (1) {
    if (task[idx + 1] == now) {
      idx++;
      if (idx >= m - 1) {
        used[now.first][now.second].push_back(time);
        break;
      }
    }
    used[now.first][now.second].push_back(time);
    time++;
    now = pre[task[idx + 1].first][task[idx + 1].second][now.first][now.second];
  }
  int ans = 0;
  REP(i, h) {
    REP(j, w) {
      if (used[i][j].empty())
        continue;
      bool light = false;
      REP(k, used[i][j].size()) {
        if (!light) {
          ans += ele[1][i][j];
        }
        if (k == used[i][j].size() - 1) {
          ans += ele[2][i][j];
          break;
        }
        if ((used[i][j][k + 1] - used[i][j][k]) * ele[0][i][j] <
            ele[1][i][j] + ele[2][i][j]) {
          ans += (used[i][j][k + 1] - used[i][j][k]) * ele[0][i][j];
          light = true;
        } else {
          ans += ele[2][i][j];
          light = false;
        }
      }
    }
  }
  cout << ans << endl;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
// #define LOG(...)
#define FOR(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define REP(i, n) for (int i = 0; i < (int)(n); ++i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())
#define RSORT(c) sort((c).rbegin(), (c).rend())
#define CLR(a) memset((a), 0, sizeof(a))
#define WRAP(x, y, w, h) (0 <= x && x < w && 0 <= y && y < h)

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<unsigned char, unsigned char> pii;
typedef pair<ll, ll> pll;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};

struct UnionFind {
  vector<int> v;
  UnionFind(int n) : v(n) {
    for (int i = 0; i < n; i++)
      v[i] = i;
  }
  int find(int x) { return v[x] == x ? x : v[x] = find(v[x]); }
  void unite(int x, int y) { v[find(x)] = find(y); }
};

int main() {
  int h, w, m;
  cin >> h >> w >> m;
  vector<string> cell(h);
  REP(i, h)
  cin >> cell[i];
  vector<vvi> ele(3, vvi(h, vi(w)));
  REP(k, 3)
  REP(i, h)
  REP(j, w)
  cin >> ele[k][i][j];
  vector<pii> task(m);
  REP(i, m)
  cin >> task[i].first >> task[i].second;
  map<pair<pii, pii>, pii> pre;
  REP(i, h) {
    REP(j, w) {
      if (cell[i][j] == '.') {
        pre[{{i, j}, {i, j}}] = {i, j};
        queue<pair<pii, pii>> Q; // now pre
        Q.push({{i, j}, {i, j}});
        while (!Q.empty()) {
          pair<pii, pii> q = Q.front();
          Q.pop();
          int ny = q.first.first;
          int nx = q.first.second;
          int py = q.second.first;
          int px = q.second.second;
          REP(k, 4) {
            if (nx + dx[k] == px && ny + dy[k] == py)
              continue;
            if (WRAP(nx + dx[k], ny + dy[k], w, h)) {
              if (cell[ny + dy[k]][nx + dx[k]] == '.') {
                pre[{{i, j}, {ny + dy[k], nx + dx[k]}}] = {ny, nx};
                Q.push({{ny + dy[k], nx + dx[k]}, {ny, nx}});
              }
            }
          }
        }
      }
    }
  }
  int time = 0;
  int idx = 0;
  pii now = task[0];
  vector<vvi> used(h, vvi(w));
  while (1) {
    if (task[idx + 1] == now) {
      idx++;
      if (idx >= m - 1) {
        used[now.first][now.second].push_back(time);
        break;
      }
    }
    used[now.first][now.second].push_back(time);
    time++;
    now = pre[{task[idx + 1], now}];
  }
  int ans = 0;
  REP(i, h) {
    REP(j, w) {
      if (used[i][j].empty())
        continue;
      bool light = false;
      REP(k, used[i][j].size()) {
        if (!light) {
          ans += ele[1][i][j];
        }
        if (k == used[i][j].size() - 1) {
          ans += ele[2][i][j];
          break;
        }
        if ((used[i][j][k + 1] - used[i][j][k]) * ele[0][i][j] <
            ele[1][i][j] + ele[2][i][j]) {
          ans += (used[i][j][k + 1] - used[i][j][k]) * ele[0][i][j];
          light = true;
        } else {
          ans += ele[2][i][j];
          light = false;
        }
      }
    }
  }
  cout << ans << endl;
}