Problem p02347 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <vector>

using namespace std;

class Point {
public:
  int id, x, y;
  Point() {}
  Point(int id, int x, int y) : id(id), x(x), y(y) {}
  bool operator<(const Point &p) const { return id < p.id; }
  void print() { printf("%d\\n", id); }
};
class Node {
public:
  int location, l, r;
};
bool lessX(const Point &p1, const Point &p2) { return p1.x < p2.x; }
bool lessY(const Point &p1, const Point &p2) { return p1.y < p2.y; }
int np = 0;
const int MAX = 500000;
Point P[MAX];
Node T[MAX];
const int NIL = -1;

int makeKdTree(int l, int r, int depth) {
  if (!(l < r))
    return NIL;

  if (depth % 2 == 0) {
    sort(P + l, P + r, lessX);
  } else {
    sort(P + l, P + r, lessY);
  }

  int t = np++;
  int mid = (l + r) / 2;
  T[t].location = mid;
  T[t].l = makeKdTree(l, mid, depth + 1);
  T[t].r = makeKdTree(mid + 1, r, depth + 1);

  return t;
}
void find(int v, int sx, int tx, int sy, int ty, int depth,
          vector<Point> &ans) {
  int x = P[T[v].location].x;
  int y = P[T[v].location].y;
  if (sx <= x && x <= tx && sy <= y && y <= ty) {
    ans.push_back(P[T[v].location]);
  }
  if (depth % 2 == 0) {
    if (T[v].l != NIL) {
      if (sx <= x)
        find(T[v].l, sx, tx, sy, ty, depth + 1, ans);
    }
    if (T[v].r != NIL) {
      if (x <= tx)
        find(T[v].r, sx, tx, sy, ty, depth + 1, ans);
    }
  } else {
    if (T[v].l != NIL) {
      if (sy <= y)
        find(T[v].l, sx, tx, sy, ty, depth + 1, ans);
    }
    if (T[v].r != NIL) {
      if (y <= ty)
        find(T[v].r, sx, tx, sy, ty, depth + 1, ans);
    }
  }
}
int main() {

  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    int x, y;
    scanf("%d %d", &x, &y);
    P[i] = Point(i, x, y);
    T[i].location = T[i].l = T[i].r = NIL;
  }

  int root = makeKdTree(0, n, 0);

  int q;
  scanf("%d", &q);
  int sx, tx, sy, ty;
  vector<Point> ans;
  for (int i = 0; i < q; ++i) {
    scanf("%d %d %d %d", &sx, &tx, &sy, &ty);
    ans.clear();
    find(root, sx, tx, sy, ty, 0, ans);
    sort(ans.begin(), ans.end());
    for (int i = 0; i < ans.size(); ++i) {
      ans[i].print();
    }
    cout << endl;
  }

  return 0;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <vector>

using namespace std;

class Point {
public:
  int id, x, y;
  Point() {}
  Point(int id, int x, int y) : id(id), x(x), y(y) {}
  bool operator<(const Point &p) const { return id < p.id; }
};
class Node {
public:
  int location, l, r;
};
bool lessX(const Point &p1, const Point &p2) { return p1.x < p2.x; }
bool lessY(const Point &p1, const Point &p2) { return p1.y < p2.y; }
int np = 0;
const int MAX = 500000;
Point P[MAX];
Node T[MAX];
const int NIL = -1;

int makeKdTree(int l, int r, int depth) {
  if (!(l < r))
    return NIL;

  if (depth % 2 == 0) {
    sort(P + l, P + r, lessX);
  } else {
    sort(P + l, P + r, lessY);
  }

  int t = np++;
  int mid = (l + r) / 2;
  T[t].location = mid;
  T[t].l = makeKdTree(l, mid, depth + 1);
  T[t].r = makeKdTree(mid + 1, r, depth + 1);

  return t;
}
void find(int v, int sx, int tx, int sy, int ty, int depth,
          vector<Point> &ans) {
  int x = P[T[v].location].x;
  int y = P[T[v].location].y;
  if (sx <= x && x <= tx && sy <= y && y <= ty) {
    ans.push_back(P[T[v].location]);
  }
  if (depth % 2 == 0) {
    if (T[v].l != NIL) {
      if (sx <= x)
        find(T[v].l, sx, tx, sy, ty, depth + 1, ans);
    }
    if (T[v].r != NIL) {
      if (x <= tx)
        find(T[v].r, sx, tx, sy, ty, depth + 1, ans);
    }
  } else {
    if (T[v].l != NIL) {
      if (sy <= y)
        find(T[v].l, sx, tx, sy, ty, depth + 1, ans);
    }
    if (T[v].r != NIL) {
      if (y <= ty)
        find(T[v].r, sx, tx, sy, ty, depth + 1, ans);
    }
  }
}
int main() {

  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    int x, y;
    scanf("%d %d", &x, &y);
    P[i] = Point(i, x, y);
    T[i].location = T[i].l = T[i].r = NIL;
  }

  int root = makeKdTree(0, n, 0);

  int q;
  scanf("%d", &q);
  int sx, tx, sy, ty;
  vector<Point> ans;
  for (int i = 0; i < q; ++i) {
    scanf("%d %d %d %d", &sx, &tx, &sy, &ty);
    ans.clear();
    find(root, sx, tx, sy, ty, 0, ans);
    sort(ans.begin(), ans.end());
    for (int i = 0; i < ans.size(); ++i) {
      cout << ans[i].id << endl;
    }
    cout << endl;
  }

  return 0;
}