Problem p02614 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define MOD (int)(1e9 + 7)
#define ceil(x, y) (x % y == 0 ? (x / y) : (x / y + 1))
#define FOR(i, N) for (int i = 0; i < N; ++i)
#define FOR1(i, N) for (int i = 1; i <= N; ++i)
#define vi vector<int>
#define pii pair<int, int>
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define mset(a, v) memset(a, v, sizeof(a))
#define all(v) (v).begin(), (v).end()
#define INF 2e18
#define EPS 1e-9
#define MAX 200009
#define int long long
/*#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef cc_hash_table<int, int, hash<int>> ht; // while using, comment #define
int long long  */

void __print(int x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}
#ifndef ONLINE_JUDGE
#define dbg(x...)                                                              \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define dbg(x...)
#endif
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
#ifndef ONLINE_JUDGE
  freopen("in2.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
#endif

  int T = 1;
  // cin >> T;
  FOR1(tt, T) {
    // cout << "Case #" << tp << ": ";
    int h, w, k;
    cin >> h >> w >> k;
    char m[h][w];
    FOR(i, h) {
      string s;
      cin >> s;
      FOR(j, w) { m[i][j] = s[j]; }
    }

    char copy[h][w];
    int ans = 0;

    for (int ci = 0; ci < (1 << h); ci++) {
      for (int cj = 0; cj < (1 << w); cj++) {
        // only last 6 bits matter atmost
        // dbg(ci, cj);
        FOR(i, h) {
          FOR(j, w) { copy[i][j] = m[i][j]; }
        }

        for (int i = 0; i < h; i++) {
          if (ci & (1 << i)) {
            // i-th row is chosen
            for (int j = 0; j < w; j++)
              copy[i][j] = '!'; // red
          }
        }

        for (int j = 0; j < w; j++) {
          if (cj & (1 << j)) {
            // j-th col is chosen
            for (int i = 0; i < h; i++)
              copy[i][j] = '!';
          }
        }

        // both row and col marked
        int black = 0;
        FOR(i, h) {
          FOR(j, w) {
            if (copy[i][j] == '#')
              black++;
          }
        }
        if (black == k)
          ans++;
      }
    }
    cout << ans;
    cout << '\\n';
  }
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define MOD (int)(1e9 + 7)
#define ceil(x, y) (x % y == 0 ? (x / y) : (x / y + 1))
#define FOR(i, N) for (int i = 0; i < N; ++i)
#define FOR1(i, N) for (int i = 1; i <= N; ++i)
#define vi vector<int>
#define pii pair<int, int>
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define mset(a, v) memset(a, v, sizeof(a))
#define all(v) (v).begin(), (v).end()
#define INF 2e18
#define EPS 1e-9
#define MAX 200009
#define int long long
/*#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef cc_hash_table<int, int, hash<int>> ht; // while using, comment #define
int long long  */

void __print(int x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}
#ifndef ONLINE_JUDGE
#define dbg(x...)                                                              \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define dbg(x...)
#endif
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
#ifndef ONLINE_JUDGE
  freopen("in2.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
#endif

  int T = 1;
  // cin >> T;
  FOR1(tt, T) {
    // cout << "Case #" << tp << ": ";
    int h, w, k;
    cin >> h >> w >> k;
    char m[h][w];
    FOR(i, h) {
      string s;
      cin >> s;
      FOR(j, w) { m[i][j] = s[j]; }
    }

    char copy[h][w];
    int ans = 0;

    for (unsigned char ci = 0; ci < 256; ci++) {
      for (unsigned char cj = 0; cj < 256; cj++) {
        // only last 6 bits matter atmost
        FOR(i, h) {
          FOR(j, w) { copy[i][j] = m[i][j]; }
        }

        for (int i = 0; i < h; i++) {
          if (ci & (1 << i)) {
            // i-th row is chosen
            for (int j = 0; j < w; j++)
              copy[i][j] = '!'; // red
          }
        }

        for (int j = 0; j < w; j++) {
          if (cj & (1 << j)) {
            // j-th col is chosen
            for (int i = 0; i < h; i++)
              copy[i][j] = '!';
          }
        }

        // both row and col marked
        int black = 0;
        FOR(i, h) {
          FOR(j, w) {
            if (copy[i][j] == '#')
              black++;
          }
        }
        if (black == k)
          ans++;
      }
    }
    cout << ans;
    // cout<<'\\n';
  }
  return 0;
}