Problem p00822 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <utility>
#include <vector>
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();
}
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 EXIST(s, e) ((s).find(e) != (s).end())
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
const double EPS = 1e-9;
const double PI = acos(-1.0);

typedef vector<vvi> vvvi;

bool satisfied(vvi &field, int y, int x) {
  FOR(i, y, y + 2) {
    FOR(j, x, x + 2) {
      if (field[i][j]) {
        return false;
      }
    }
  }
  return true;
}

int h(int y, int x) { return y * 3 + x; }

bool thirsty(vi pos) {
  vvi wetness(4, vi(4));
  REP(i, pos.size()) {
    int y = pos[i] / 3;
    int x = pos[i] % 3;
    FOR(j, y, y + 2) {
      FOR(k, x, x + 2) { wetness[j][k]++; }
    }
  }
  REP(i, 4) {
    REP(j, 4) {
      if (wetness[i][j] == 0) {
        return true;
      }
    }
  }
  return false;
}

int dp[2][9][9][9][9][9][9];
int main() {
  int N;
  while (cin >> N, N) {
    REP(day, 2)
    REP(i, 9) REP(j, 9) REP(k, 9) REP(l, 9) REP(m, 9) REP(n, 9)
        dp[day][i][j][k][l][m][n] = 0;
    int d = 0;
    REP(day, N) {
      vvi field(4, vi(4));
      REP(i, 4) {
        REP(j, 4) { cin >> field[i][j]; }
      }
      REP(i, 9)
      REP(j, 9) REP(k, 9) REP(l, 9) REP(m, 9) REP(n, 9)
          dp[d][i][j][k][l][m][n] = 0;
      if (day == 0) {
        dp[d][0][0][0][0][0][h(1, 1)] = satisfied(field, 1, 1);
      } else {
        REP(i, 9) {
          REP(j, 9) {
            REP(k, 9) {
              REP(l, 9) {
                REP(m, 9) {
                  REP(n, 9) {
                    if (dp[(d + 1) % 2][i][j][k][l][m][n]) {
                      int py = n / 3, px = n % 3;
                      REP(o, 9) {
                        int cy = o / 3, cx = o % 3;
                        if (cy == py || cx == px) {
                          if (day >= 6) {
                            vi pos;
                            pos.push_back(i);
                            pos.push_back(j);
                            pos.push_back(k);
                            pos.push_back(l);
                            pos.push_back(m);
                            pos.push_back(n);
                            pos.push_back(o);
                            if (thirsty(pos))
                              continue;
                          }
                          dp[d][j][k][l][m][n][o] |= satisfied(field, cy, cx);
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
      d = (d + 1) % 2;
    }
    bool ok = false;
    REP(i, 9) {
      REP(j, 9) {
        REP(k, 9) {
          REP(l, 9) {
            REP(m, 9) {
              REP(n, 9) { ok |= dp[(d + 1) % 2][i][j][k][l][m][n]; }
            }
          }
        }
      }
    }
    cout << ok << endl;
  }
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <utility>
#include <vector>
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();
}
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 EXIST(s, e) ((s).find(e) != (s).end())
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
const double EPS = 1e-9;
const double PI = acos(-1.0);

typedef vector<vvi> vvvi;

bool satisfied(vvi &field, int y, int x) {
  FOR(i, y, y + 2) {
    FOR(j, x, x + 2) {
      if (field[i][j]) {
        return false;
      }
    }
  }
  return true;
}

int h(int y, int x) { return y * 3 + x; }

bool thirsty(vi pos) {
  vvi wetness(4, vi(4));
  REP(i, pos.size()) {
    int y = pos[i] / 3;
    int x = pos[i] % 3;
    FOR(j, y, y + 2) {
      FOR(k, x, x + 2) { wetness[j][k]++; }
    }
  }
  REP(i, 4) {
    REP(j, 4) {
      if (wetness[i][j] == 0) {
        return true;
      }
    }
  }
  return false;
}

int dp[2][9][9][9][9][9][9];
int main() {
  int N;
  while (cin >> N, N) {
    REP(day, 2)
    REP(i, 9) REP(j, 9) REP(k, 9) REP(l, 9) REP(m, 9) REP(n, 9)
        dp[day][i][j][k][l][m][n] = 0;
    int d = 0;
    REP(day, N) {
      vvi field(4, vi(4));
      REP(i, 4) {
        REP(j, 4) { cin >> field[i][j]; }
      }
      REP(i, 9)
      REP(j, 9) REP(k, 9) REP(l, 9) REP(m, 9) REP(n, 9)
          dp[d][i][j][k][l][m][n] = 0;
      if (day == 0) {
        dp[d][0][0][0][0][0][h(1, 1)] = satisfied(field, 1, 1);
      } else {
        REP(i, 9) {
          REP(j, 9) {
            REP(k, 9) {
              REP(l, 9) {
                REP(m, 9) {
                  REP(n, 9) {
                    int py = n / 3, px = n % 3;
                    REP(o, 9) {
                      int cy = o / 3, cx = o % 3;
                      if (cy == py || cx == px) {
                        if (dp[(d + 1) % 2][i][j][k][l][m][n]) {
                          if (day >= 6) {
                            vi pos;
                            pos.push_back(i);
                            pos.push_back(j);
                            pos.push_back(k);
                            pos.push_back(l);
                            pos.push_back(m);
                            pos.push_back(n);
                            pos.push_back(o);
                            if (thirsty(pos))
                              continue;
                          }
                          dp[d][j][k][l][m][n][o] |= satisfied(field, cy, cx);
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
      d = (d + 1) % 2;
    }
    bool ok = false;
    REP(i, 9) {
      REP(j, 9) {
        REP(k, 9) {
          REP(l, 9) {
            REP(m, 9) {
              REP(n, 9) { ok |= dp[(d + 1) % 2][i][j][k][l][m][n]; }
            }
          }
        }
      }
    }
    cout << ok << endl;
  }
}