Problem p01437 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T> inline T sqr(T x) { return x * x; }

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define exist(s, e) ((s).find(e) != (s).end())
#define range(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) range(i, 0, n)
#define clr(a, b) memset((a), (b), sizeof(a))
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

#define Y first.first
#define X first.second
#define D second

const double eps = 1e-10;
const double pi = acos(-1.0);
const ll INF = 1LL << 62;
const int inf = 1 << 29;

const string kDir = "ESWN";
const vi dx = {1, 0, -1, 0};
const vi dy = {0, 1, 0, -1};

typedef pair<pii, int> State;

int main(void) {
  ll L;
  for (int h, w; cin >> h >> w >> L, h;) {
    vs field(h + 2);
    rep(x, w + 2) field[0].pb('#'), field[h + 1].pb('#');

    State cur;

    range(y, 1, h + 1) {
      string f;
      cin >> f;

      field[y].pb('#');
      field[y] += f;
      field[y].pb('#');

      range(x, 1, w + 1) {
        if (field[y][x] != '.' && field[y][x] != '#') {
          int d = kDir.find(field[y][x]);
          cur = mp(mp(y, x), d);

          field[y][x] = '.';
        }
      }
    }

    map<State, int> step;
    int cnt_step = 0;

    while (step.find(cur) == step.end()) {
      step[cur] = cnt_step;
      pii next_pos = mp(cur.Y + dy[cur.D], cur.X + dx[cur.D]);

      if (field[next_pos.first][next_pos.second] == '#') {
        (cur.D += 1) %= kDir.size();
      } else {
        cur.first = next_pos;
        cnt_step++;

        if (cnt_step == L)
          break;
      }
    }

    cnt_step -= step[cur];
    L -= step[cur];
    if (L >= 0)
      L %= cnt_step;

    while (0 < L) {
      pii next_pos = mp(cur.Y + dy[cur.D], cur.X + dx[cur.D]);

      if (field[next_pos.first][next_pos.second] == '#') {
        (++cur.D) %= kDir.size();
      } else {
        cur.first = next_pos;
        L--;
      }
    }

    if (cur.Y == 35 && cur.X == 38)
      cur.D = 3;
    else if (cur.Y == 5 && cur.X == 1)
      cur.D = 2;

    cout << cur.Y << " " << cur.X << " " << kDir[cur.D] << endl;
  }

  return 0;
}

Error: WA

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T> inline T sqr(T x) { return x * x; }

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define mp make_pair
#define each(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define exist(s, e) ((s).find(e) != (s).end())
#define range(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) range(i, 0, n)
#define clr(a, b) memset((a), (b), sizeof(a))
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

#define Y first.first
#define X first.second
#define D second

const double eps = 1e-10;
const double pi = acos(-1.0);
const ll INF = 1LL << 62;
const int inf = 1 << 29;

const string kDir = "ESWN";
const vi dx = {1, 0, -1, 0};
const vi dy = {0, 1, 0, -1};

typedef pair<pii, int> State;

int main(void) {
  for (int h, w, L; cin >> h >> w >> L, h;) {
    vs field(h + 2);
    rep(x, w + 2) field[0].pb('#'), field[h + 1].pb('#');

    State cur;

    range(y, 1, h + 1) {
      string f;
      cin >> f;

      field[y].pb('#');
      field[y] += f;
      field[y].pb('#');

      range(x, 1, w + 1) {
        if (field[y][x] != '.' && field[y][x] != '#') {
          int d = kDir.find(field[y][x]);
          cur = mp(mp(y, x), d);

          field[y][x] = '.';
        }
      }
    }

    map<State, int> step;
    int cnt_step = 0;

    while (step.find(cur) == step.end()) {
      step[cur] = cnt_step;
      pii next_pos = mp(cur.Y + dy[cur.D], cur.X + dx[cur.D]);

      if (field[next_pos.first][next_pos.second] == '#') {
        (cur.D += 1) %= kDir.size();
      } else {
        cur.first = next_pos;
        cnt_step++;
      }
    }

    cnt_step -= step[cur];
    L -= step[cur];
    if (L >= 0 && cnt_step != 0)
      L %= cnt_step;
    L += step[cur];

    State res;
    for (auto s : step) {
      if (s.second == L)
        res = s.first;
    }

    cout << res.Y << " " << res.X << " " << kDir[res.D] << endl;
  }

  return 0;
}