Problem p01296 (C++) — buggy submission, verdict: Time Limit Exceeded

#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;

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

pii in[40010];

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};

int main(void) {
  int n;
  while (cin >> n) {
    if (n == 0)
      break;

    map<pii, int> memo;
    bool check[40010];
    rep(i, 2 * n) check[i] = false;
    rep(i, n) {
      char dir;
      cin >> in[2 * i].first >> in[2 * i].second >> dir;
      in[2 * i + 1] = in[2 * i];
      int d = (dir == 'x') ? 2 : 3;
      in[2 * i + 1].first += dx[d], in[2 * i + 1].second += dy[d];
      memo[in[2 * i]] = 2 * i;
      memo[in[2 * i + 1]] = 2 * i + 1;
    }

    bool ans = true;
    rep(i, n) {
      if (check[2 * i])
        continue;
      bool ok = false;
      rep(j, 2) {
        bool ok2 = true;
        map<int, int> color;
        queue<int> q;

        color[2 * i] = j;
        color[2 * i + 1] = j ^ 1;
        check[2 * i] = true;
        check[2 * i + 1] = true;
        q.push(2 * i);
        q.push(2 * i + 1);

        while (!q.empty()) {
          int cur = q.front();
          q.pop();
          pii xy = in[cur];
          rep(l, 4) {
            pii next = xy;
            next.first += dx[l], next.second += dy[l];
            if (memo.find(next) == memo.end())
              continue;
            int index = memo[next];
            if (color.find(index) == color.end()) {
              color[index] = color[cur];
              color[index ^ 1] = color[cur] ^ 1;
              check[index] = true;
              check[index ^ 1] = true;
              q.push(index);
              q.push(index ^ 1);
            } else if ((cur ^ 1) != index && color[index] != color[cur])
              ok2 = false;
          }
        }
        if (ok2)
          ok = true;
      }
      if (!ok)
        ans = false;
    }
    if (ans)
      puts("Yes");
    else
      puts("No");
  }
  return 0;
}

Error: TLE

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;

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

pii in[40010];

bool check[40010];

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};

int main(void) {
  int n;
  while (cin >> n) {
    if (n == 0)
      break;

    map<pii, int> memo;
    rep(i, n) {
      char dir;
      cin >> in[2 * i].first >> in[2 * i].second >> dir;
      in[2 * i + 1] = in[2 * i];
      int d = (dir == 'x') ? 2 : 3;
      in[2 * i + 1].first += dx[d], in[2 * i + 1].second += dy[d];
      memo[in[2 * i]] = 2 * i;
      memo[in[2 * i + 1]] = 2 * i + 1;
    }
    clr(check, false);

    bool ans = true;
    rep(i, n) {
      if (check[2 * i])
        continue;
      bool ok = false;
      rep(j, 2) {
        bool ok2 = true;
        map<int, int> color;
        queue<int> q;

        color[2 * i] = j;
        color[2 * i + 1] = j ^ 1;
        q.push(2 * i);
        q.push(2 * i + 1);

        while (!q.empty()) {
          int cur = q.front();
          q.pop();
          pii xy = in[cur];
          rep(l, 4) {
            pii next = xy;
            next.first += dx[l], next.second += dy[l];
            if (memo.find(next) == memo.end())
              continue;
            int index = memo[next];
            if (color.find(index) == color.end()) {
              color[index] = color[cur];
              color[index ^ 1] = color[cur] ^ 1;
              q.push(index);
              q.push(index ^ 1);
            } else if ((cur ^ 1) != index && color[index] != color[cur])
              ok2 = false;
          }
        }
        if (ok2) {
          ok = true;
          for (auto &k : color)
            check[k.second] = true;
        }
      }
      if (!ok)
        ans = false;
    }
    if (ans)
      puts("Yes");
    else
      puts("No");
  }
  return 0;
}