Problem p00454 (C++)

Buggy submission (status: Memory Limit Exceeded):
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

typedef long long LL;
typedef long double LD;
typedef pair<int, int> P;
typedef pair<int, P> P1;

#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define rep(i, x) for (int i = 0; i < x; i++)
#define rep1(i, x) for (int i = 1; i <= x; i++)
#define rrep(i, x) for (int i = x - 1; i >= 0; i--)
#define rrep1(i, x) for (int i = x; i > 0; i--)
#define sor(v) sort(v.begin(), v.end())
#define rev(s) reverse(s.begin(), s.end())
#define lb(vec, a) lower_bound(vec.begin(), vec.end(), a)
#define ub(vec, a) upper_bound(vec.begin(), vec.end(), a)
#define uniq(vec) vec.erase(unique(vec.begin(), vec.end()), vec.end())
#define min_3(a, b, c) min(a, min(b, c))
#define max_3(a, b, c) max(a, max(b, c))
#define mp1(a, b, c) P1(a, P(b, c))
#define pque(a) priority_queue<a>
#define rpque(a) priority_queue<a, vector<a>, greater<a>>

const int INF = 1000000000;
const int dre_4[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
const int dre_8[8][2] = {{1, 0},  {1, 1},   {0, 1},  {-1, 1},
                         {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
const int kaijou[10] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};

int imos[3010][3010];
int a[3010][3010];

int dfs(int x, int y) {
  if (a[x][y])
    return 0;
  a[x][y] = 1;
  rep(i, 4) dfs(x + dre_4[i][0], y + dre_4[i][1]);
  return 1;
}

int main() {
  while (1) {
    int w, h, n;
    int x1[1010], y1[1010], x2[1010], y2[1010];
    scanf("%d%d", &w, &h);
    if (w == 0 && h == 0)
      break;
    scanf("%d", &n);
    rep(i, n) scanf("%d%d%d%d", &x1[i], &y1[i], &x2[i], &y2[i]);

    vector<int> R, C;
    R.pb(0);
    R.pb(w);
    C.pb(0);
    C.pb(h);
    rep(i, n) {
      R.pb(x1[i]);
      R.pb(x2[i]);
      C.pb(y1[i]);
      C.pb(y2[i]);
    }
    sor(R);
    uniq(R);
    sor(C);
    uniq(C);

    w = lb(R, w) - R.begin();
    h = lb(C, h) - C.begin();
    rep(i, n) {
      x1[i] = lb(R, x1[i]) - R.begin();
      y1[i] = lb(C, y1[i]) - C.begin();
      x2[i] = lb(R, x2[i]) - R.begin();
      y2[i] = lb(C, y2[i]) - C.begin();
    }

    rep(i, 3010) rep(j, 3010) imos[i][j] = 0;
    rep(i, 3010) rep(j, 3010) a[i][j] = 1;

    rep(i, n) {
      imos[x1[i]][y1[i]]++;
      imos[x1[i]][y2[i]]--;
      imos[x2[i]][y1[i]]--;
      imos[x2[i]][y2[i]]++;
    }

    rep(i, 3010) rep1(j, 3009) imos[i][j] += imos[i][j - 1];
    rep1(i, 3009) rep(j, 3010) imos[i][j] += imos[i - 1][j];

    rep1(i, R.size() - 1) rep1(j, C.size() - 1) a[i][j] = imos[i - 1][j - 1];

    /*rep(i,20){
            rep(j,10){
                    printf("%d",a[i][j]);
            }
            puts("");
    }*/

    int cnt = 0;
    rep(i, 3010) rep(j, 3010) cnt += dfs(i, j);

    printf("%d\n", cnt);
  }
}

Fixed submission:
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

typedef long long LL;
typedef long double LD;
typedef pair<int, int> P;
typedef pair<int, P> P1;

#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define rep(i, x) for (int i = 0; i < x; i++)
#define rep1(i, x) for (int i = 1; i <= x; i++)
#define rrep(i, x) for (int i = x - 1; i >= 0; i--)
#define rrep1(i, x) for (int i = x; i > 0; i--)
#define sor(v) sort(v.begin(), v.end())
#define rev(s) reverse(s.begin(), s.end())
#define lb(vec, a) lower_bound(vec.begin(), vec.end(), a)
#define ub(vec, a) upper_bound(vec.begin(), vec.end(), a)
#define uniq(vec) vec.erase(unique(vec.begin(), vec.end()), vec.end())
#define min_3(a, b, c) min(a, min(b, c))
#define max_3(a, b, c) max(a, max(b, c))
#define mp1(a, b, c) P1(a, P(b, c))
#define pque(a) priority_queue<a>
#define rpque(a) priority_queue<a, vector<a>, greater<a>>

const int INF = 1000000000;
const int dre_4[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
const int dre_8[8][2] = {{1, 0},  {1, 1},   {0, 1},  {-1, 1},
                         {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
const int kaijou[10] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};

short imos[3010][3010];
short a[3010][3010];

int dfs(int x, int y) {
  if (a[x][y])
    return 0;
  a[x][y] = 1;
  rep(i, 4) dfs(x + dre_4[i][0], y + dre_4[i][1]);
  return 1;
}

int main() {
  while (1) {
    int w, h, n;
    int x1[1010], y1[1010], x2[1010], y2[1010];
    scanf("%d%d", &w, &h);
    if (w == 0 && h == 0)
      break;
    scanf("%d", &n);
    rep(i, n) scanf("%d%d%d%d", &x1[i], &y1[i], &x2[i], &y2[i]);

    vector<int> R, C;
    R.pb(0);
    R.pb(w);
    C.pb(0);
    C.pb(h);
    rep(i, n) {
      R.pb(x1[i]);
      R.pb(x2[i]);
      C.pb(y1[i]);
      C.pb(y2[i]);
    }
    sor(R);
    uniq(R);
    sor(C);
    uniq(C);

    w = lb(R, w) - R.begin();
    h = lb(C, h) - C.begin();
    rep(i, n) {
      x1[i] = lb(R, x1[i]) - R.begin();
      y1[i] = lb(C, y1[i]) - C.begin();
      x2[i] = lb(R, x2[i]) - R.begin();
      y2[i] = lb(C, y2[i]) - C.begin();
    }

    rep(i, 3010) rep(j, 3010) imos[i][j] = 0;
    rep(i, 3010) rep(j, 3010) a[i][j] = 1;

    rep(i, n) {
      imos[x1[i]][y1[i]]++;
      imos[x1[i]][y2[i]]--;
      imos[x2[i]][y1[i]]--;
      imos[x2[i]][y2[i]]++;
    }

    rep(i, 3010) rep1(j, 3009) imos[i][j] += imos[i][j - 1];
    rep1(i, 3009) rep(j, 3010) imos[i][j] += imos[i - 1][j];

    rep1(i, R.size() - 1) rep1(j, C.size() - 1) a[i][j] = imos[i - 1][j - 1];

    /*rep(i,20){
            rep(j,10){
                    printf("%d",a[i][j]);
            }
            puts("");
    }*/

    int cnt = 0;
    rep(i, 3010) rep(j, 3010) cnt += dfs(i, j);

    printf("%d\n", cnt);
  }
}