Problem p00481 (C++) — buggy submission, verdict: Memory Limit Exceeded

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define ALL(co) co.begin(), co.end()
#define tpl(...) make_tuple(__VA_ARGS__)

typedef long long LL;
typedef pair<int, int> P;
typedef pair<P, int> PI;
typedef pair<P, P> PP;
typedef vector<int> Array;
typedef vector<vector<int>> Array2;
typedef vector<LL> LArray;
typedef vector<P> PArray;
typedef vector<string> SArray;

const int INF = 1 << 29;
const LL LINF = 1LL << 60;

inline int getInt() {
  int itiv;
  return (cin >> itiv, itiv);
}
template <typename T> void readAll(vector<T> &vec) {
  for (int i = 0, size = vec.size(); i < size; i++)
    cin >> vec[i];
}
template <typename T, typename U> void readAll(vector<pair<T, U>> &vec) {
  for (int i = 0, size = vec.size(); i < size; i++)
    cin >> vec[i].first >> vec[i].second;
}
template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};
inline bool between(int min, int max, int n) { return min <= n && n <= max; }
inline bool inRange(int begin, int end, int n) { return begin <= n && n < end; }
inline bool inRange(int size, int n) { return 0 <= n && n < size; }

int dx[] = {-1, 0, 1, 0}, dy[] = {0, -1, 0, 1};
int dr[] = {0, -1, 0, 1}, dc[] = {-1, 0, 1, 0};
bool visited[1000][1000];
char stage[1000][1000];
int h, w, n;

int main(void) {
  ios::sync_with_stdio(false);
  while (cin >> h >> w >> n && n) {
    PArray goals(n + 1);
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        cin >> stage[i][j];
        if (stage[i][j] == 'S')
          goals[0] = P(i, j);
        int num = stage[i][j] - '0';
        if (inRange(n + 1, num))
          goals[num] = P(i, j);
      }
    }

    int ans = 0;
    for (int i = 0; i < n; i++) {
      P start = goals[i], goal = goals[i + 1];
      memset(visited, false, sizeof(visited));
      queue<PI> que;
      que.push(PI(start, 0));
      while (!que.empty()) {
        PI pi = que.front();
        que.pop();
        if (goal == pi.first) {
          ans += pi.second;
          break;
        }
        int r = pi.first.first, c = pi.first.second;

        for (int i = 0; i < 4; i++) {
          int nr = r + dr[i], nc = c + dc[i];
          if (!inRange(h, nr) || !inRange(w, nc) || stage[nr][nc] == 'X' ||
              visited[nr][nc])
            continue;
          que.push(PI(P(nr, nc), pi.second + 1));
          visited[nr][nc] = true;
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}

Error: MLE

Fixed submission:

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define ALL(co) co.begin(), co.end()
#define tpl(...) make_tuple(__VA_ARGS__)

typedef long long LL;
typedef pair<int, int> P;
typedef pair<P, int> PI;
typedef pair<P, P> PP;
typedef vector<int> Array;
typedef vector<vector<int>> Array2;
typedef vector<LL> LArray;
typedef vector<P> PArray;
typedef vector<string> SArray;

const int INF = 1 << 29;
const LL LINF = 1LL << 60;

inline int getInt() {
  int itiv;
  return (cin >> itiv, itiv);
}
template <typename T> void readAll(vector<T> &vec) {
  for (int i = 0, size = vec.size(); i < size; i++)
    cin >> vec[i];
}
template <typename T, typename U> void readAll(vector<pair<T, U>> &vec) {
  for (int i = 0, size = vec.size(); i < size; i++)
    cin >> vec[i].first >> vec[i].second;
}
template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};
inline bool between(int min, int max, int n) { return min <= n && n <= max; }
inline bool inRange(int begin, int end, int n) { return begin <= n && n < end; }
inline bool inRange(int size, int n) { return 0 <= n && n < size; }

int dx[] = {-1, 0, 1, 0}, dy[] = {0, -1, 0, 1};
int dr[] = {0, -1, 0, 1}, dc[] = {-1, 0, 1, 0};
bool visited[1000][1000];
char stage[1000][1000];
int h, w, n;

int main(void) {
  ios::sync_with_stdio(false);
  while (cin >> h >> w >> n && n) {
    PArray goals(n + 1);
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        cin >> stage[i][j];
        if (stage[i][j] == 'S')
          goals[0] = P(i, j);
        int num = stage[i][j] - '0';
        if (inRange(n + 1, num))
          goals[num] = P(i, j);
      }
    }

    int ans = 0;
    for (int i = 0; i < n; i++) {
      P start = goals[i], goal = goals[i + 1];
      memset(visited, false, sizeof(visited));
      queue<PI> que;
      que.push(PI(start, 0));
      while (!que.empty()) {
        PI pi = que.front();
        que.pop();
        if (goal == pi.first) {
          ans += pi.second;
          break;
        }
        int r = pi.first.first, c = pi.first.second;

        for (int i = 0; i < 4; i++) {
          int nr = r + dr[i], nc = c + dc[i];
          if (!inRange(h, nr) || !inRange(w, nc) || stage[nr][nc] == 'X' ||
              visited[nr][nc])
            continue;
          que.push(PI(P(nr, nc), pi.second + 1));
          visited[r][c] = true;
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}