Problem p00966 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(c) (c).begin(), (c).end()
#define pb push_back
#define dbg(...)                                                               \\
  do {                                                                         \\
    cerr << __LINE__ << ": ";                                                  \\
    dbgprint(#__VA_ARGS__, __VA_ARGS__);                                       \\
  } while (0);

using namespace std;

namespace std {
template <class S, class T> struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T> struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v)
      h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
} // namespace std
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  rep(i, v.size()) os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v)
    os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v)
    os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;

int n, a, b, q;

int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  cin >> n >> a >> b >> q;
  vector<pair<int, char>> xs;
  rep(i, a) {
    int x;
    char c;
    cin >> x >> c;
    xs.emplace_back(--x, c);
  }

  vector<pi> ys;
  rep(i, b) {
    int y, h;
    cin >> y >> h;
    ys.emplace_back(--y, --h);
  }
  if (ys.size() && ys.back().second >= 0)
    ys.emplace_back(n, -1);

  map<pi, int> left;
  rep(i, ys.size()) {
    if (ys[i].second < 0)
      continue;
    int L = ys[i].first, R = ys[i + 1].first;
    int l = ys[i].second, r = l + R - L, d = L - l;
    left[pi(L, R)] = d;
  }

  auto move = [&](int p) {
    map<pi, int>::iterator it = left.lower_bound(pi(p + 1, 0));
    if (it == left.begin())
      return p;
    --it;

    if (!(it->first.first <= p && p < it->first.second))
      return p;
    int l = it->first.first - it->second, t = (p - l) / it->second;
    return p - t * it->second;
  };

  unordered_map<int, char> cs;
  for (auto i : xs) {
    int p = i.first;
    for (int nxt = p; p != (nxt = move(p)); p = nxt)
      ;
    cs[p] = i.second;
  }
  /*
  for(auto p : cs) dbg(p.first, p.second);
  for(auto p : left) dbg(p.first, p.second);
  */
  string ans;
  while (q--) {
    int p;
    cin >> p;
    for (int nxt = --p; p != (nxt = move(p)); p = nxt)
      ;
    ans += cs.count(p) ? cs[p] : '?';
  }
  cout << ans << endl;
  return 0;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(c) (c).begin(), (c).end()
#define pb push_back
#define dbg(...)                                                               \\
  do {                                                                         \\
    cerr << __LINE__ << ": ";                                                  \\
    dbgprint(#__VA_ARGS__, __VA_ARGS__);                                       \\
  } while (0);

using namespace std;

namespace std {
template <class S, class T> struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T> struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v)
      h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
} // namespace std
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  rep(i, v.size()) os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v)
    os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v)
    os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;

int n, a, b, q;

int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  cin >> n >> a >> b >> q;
  vector<pair<int, char>> xs;
  rep(i, a) {
    int x;
    char c;
    cin >> x >> c;
    xs.emplace_back(--x, c);
  }

  vector<pi> ys;
  rep(i, b) {
    int y, h;
    cin >> y >> h;
    ys.emplace_back(--y, --h);
  }
  if (ys.back().second >= 0)
    ys.emplace_back(n, -1);

  map<pi, int> left;
  rep(i, ys.size()) {
    if (ys[i].second < 0)
      continue;
    while (i == ys.size() - 1)
      ;
    int L = ys[i].first, R = ys[i + 1].first;
    int l = ys[i].second, r = l + R - L, d = L - l;
    left[pi(L, R)] = d;
  }

  auto move = [&](int p) {
    map<pi, int>::iterator it = left.lower_bound(pi(p + 1, 0));
    if (it == left.begin())
      return p;
    --it;

    if (!(it->first.first <= p && p < it->first.second))
      return p;
    while (it->second == 0)
      ;
    int l = it->first.first - it->second, t = (p - l) / it->second;
    return p - t * it->second;
  };

  map<int, char> cs;
  for (auto i : xs) {
    int p = i.first;
    for (int nxt = p; p != (nxt = move(p)); p = nxt)
      ;
    cs[p] = i.second;
  }
  /*
  for(auto p : cs) dbg(p.first, p.second);
  for(auto p : left) dbg(p.first, p.second);
  */
  string ans;
  while (q--) {
    int p;
    cin >> p;
    for (int nxt = --p; p != (nxt = move(p)); p = nxt)
      ;
    ans += cs.count(p) ? cs[p] : '?';
  }
  cout << ans << endl;
  return 0;
}