Problem p00454 (C++) — buggy submission, verdict: Memory Limit Exceeded

#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;
typedef pair<int, int> P;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-9
#define INF 2000000000
#define sz(x) ((int)(x).size())
#define fi first
#define sec second
#define SORT(x) sort((x).begin(), (x).end())
#define all(x) (x).begin(), (x).end()
#define EQ(a, b) (abs((a) - (b)) < EPS)
int X1[1005], X2[1005], Y1[1005], Y2[1005];
int f[3030][3030];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int W, H, N;
int ans = 0;
int compress(int *x1, int *x2, int t) {
  vector<int> xs;
  for (int i = 0; i < N; i++) {
    int tx1 = x1[i], tx2 = x2[i];
    if (1 <= tx1 && tx1 < t)
      xs.pb(tx1);
    if (1 <= tx2 && tx2 < t)
      xs.pb(tx2);
  }
  xs.pb(0);
  xs.pb(t);
  SORT(xs);
  xs.erase(unique(all(xs)), xs.end());
  for (int i = 0; i < N; i++) {
    x1[i] = find(all(xs), x1[i]) - xs.begin();
    x2[i] = find(all(xs), x2[i]) - xs.begin();
  }
  return xs.size() - 1;
}
int main() {
  while (1) {
    memset(f, 0, sizeof(f));
    ans = 0;
    cin >> W >> H;
    if (W == 0 && H == 0)
      return 0;
    cin >> N;
    for (int i = 0; i < N; i++) {
      cin >> X1[i] >> Y1[i] >> X2[i] >> Y2[i];
    }
    W = compress(X1, X2, W);
    H = compress(Y1, Y2, H);
    for (int i = 0; i < N; i++) {
      f[Y1[i]][X1[i]]++;
      f[Y2[i]][X2[i]]++;
      f[Y1[i]][X2[i]]--;
      f[Y2[i]][X1[i]]--;
    }
    for (int i = 0; i < H; i++) {
      for (int j = 1; j < W; j++) {
        f[i][j] += f[i][j - 1];
      }
    }
    for (int i = 1; i < H; i++) {
      for (int j = 0; j < W; j++) {
        f[i][j] += f[i - 1][j];
      }
    }
    for (int i = 0; i < H; i++) {
      for (int j = 0; j < W; j++) {
        if (f[i][j])
          continue;
        ans++;
        queue<P> q;
        q.push(mp(j, i));
        while (!q.empty()) {
          int tx = q.front().fi, ty = q.front().sec;
          q.pop();
          for (int k = 0; k < 4; k++) {
            int ttx = tx + dx[k], tty = ty + dy[k];
            if (ttx < 0 || ttx > W || tty < 0 || tty > H || f[tty][ttx] > 0)
              continue;
            q.push(mp(ttx, tty));
            f[tty][ttx] = 1;
          }
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}

Error: MLE

Fixed submission:

#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;
typedef pair<int, int> P;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-9
#define INF 2000000000
#define sz(x) ((int)(x).size())
#define fi first
#define sec second
#define SORT(x) sort((x).begin(), (x).end())
#define all(x) (x).begin(), (x).end()
#define EQ(a, b) (abs((a) - (b)) < EPS)
int X1[1005], X2[1005], Y1[1005], Y2[1005];
int f[6030][6030];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int W, H, N;
int ans = 0;
int compress(int *x1, int *x2, int t) {
  vector<int> xs;
  for (int i = 0; i < N; i++) {
    int tx1 = x1[i], tx2 = x2[i];
    if (1 <= tx1 && tx1 < t)
      xs.pb(tx1);
    if (1 <= tx2 && tx2 < t)
      xs.pb(tx2);
  }
  xs.pb(0);
  xs.pb(t);
  SORT(xs);
  xs.erase(unique(all(xs)), xs.end());
  for (int i = 0; i < N; i++) {
    x1[i] = find(all(xs), x1[i]) - xs.begin();
    x2[i] = find(all(xs), x2[i]) - xs.begin();
  }
  return xs.size() - 1;
}
int main() {
  while (1) {
    memset(f, 0, sizeof(f));
    ans = 0;
    cin >> W >> H;
    if (W == 0 && H == 0)
      return 0;
    cin >> N;
    for (int i = 0; i < N; i++) {
      cin >> X1[i] >> Y1[i] >> X2[i] >> Y2[i];
    }
    W = compress(X1, X2, W);
    H = compress(Y1, Y2, H);
    for (int i = 0; i < N; i++) {
      f[Y1[i]][X1[i]]++;
      f[Y2[i]][X2[i]]++;
      f[Y1[i]][X2[i]]--;
      f[Y2[i]][X1[i]]--;
    }
    for (int i = 0; i < H; i++) {
      for (int j = 1; j < W; j++) {
        f[i][j] += f[i][j - 1];
      }
    }
    for (int i = 1; i < H; i++) {
      for (int j = 0; j < W; j++) {
        f[i][j] += f[i - 1][j];
      }
    }
    for (int i = 0; i < H; i++) {
      for (int j = 0; j < W; j++) {
        if (f[i][j])
          continue;
        ans++;
        queue<P> q;
        q.push(mp(j, i));
        while (!q.empty()) {
          int tx = q.front().fi, ty = q.front().sec;
          q.pop();
          for (int k = 0; k < 4; k++) {
            int ttx = tx + dx[k], tty = ty + dy[k];
            if (ttx < 0 || ttx > W || tty < 0 || tty > H || f[tty][ttx] > 0)
              continue;
            q.push(mp(ttx, tty));
            f[tty][ttx] = 1;
          }
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}