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

#include <algorithm>
#include <cstdio>
#include <vector>
using namespace std;

struct Node {
  int location;
  int p, l, r;
  Node() {}
};

struct Point {
  int x;
  int y;
  int index;
  Point() {}
  Point(int x, int y, int index) : x(x), y(y), index(index) {}
  bool operator<(const Point &o) const { return index < o.index; }
};
static const int MAX = 1000000;
static const int NIL = -1;
Point P[MAX];
Node T[MAX];
int N;
int np;

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 makekDTree(int l, int r, int depth) {
  if (!(l < r))
    return NIL;
  int mid = (l + r) / 2;
  int t = np++;
  if (depth % 2 == 0) {
    sort(P + l, P + r, lessX);
  } else {
    sort(P + l, P + r, lessY);
  }
  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() {
  scanf("%d", &N);
  for (int i = 0; i < N; i++) {
    int x, y;
    scanf("%d %d", &x, &y);
    P[i] = Point(x, y, i);
    T[i].l = T[i].r = T[i].p = NIL;
  }
  np = 0;
  int root = makekDTree(0, N, 0);
  int q;
  scanf("%d", &q);
  vector<Point> ans;
  for (int i = 0; i < q; i++) {
    int sx, tx, sy, ty;
    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 (auto &p : ans) {
      printf("%d\\n", p.index);
    }
    printf("\\n");
  }
  return 0;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

struct Node {
  int location;
  int p, l, r;
  Node() {}
};

struct Point {
  int x;
  int y;
  int index;
  Point() {}
  Point(int x, int y, int index) : x(x), y(y), index(index) {}
  bool operator<(const Point &o) const { return index < o.index; }
};
static const int MAX = 1000000;
static const int NIL = -1;
Point P[MAX];
Node T[MAX];
int N;
int np;

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 makekDTree(int l, int r, int depth) {
  if (!(l < r))
    return NIL;
  int mid = (l + r) / 2;
  int t = np++;
  if (depth % 2 == 0) {
    sort(P + l, P + r, lessX);
  } else {
    sort(P + l, P + r, lessY);
  }
  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() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> N;
  for (int i = 0; i < N; i++) {
    int x, y;
    cin >> x >> y;
    P[i] = Point(x, y, i);
    T[i].l = T[i].r = T[i].p = NIL;
  }
  np = 0;
  int root = makekDTree(0, N, 0);
  int q;
  cin >> q;
  vector<Point> ans;
  for (int i = 0; i < q; i++) {
    int sx, tx, sy, ty;
    cin >> sx >> tx >> sy >> ty;
    ans.clear();
    find(root, sx, tx, sy, ty, 0, ans);
    sort(ans.begin(), ans.end());
    for (auto &p : ans) {
      cout << p.index << endl;
    }
    cout << endl;
  }
  return 0;
}