Problem p03585 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <string>
#include <vector>
//    #include <boost/multiprecision/cpp_int.hpp>
#include <functional>
#define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, double>
#define ppap pair<pa, int>
#define PI 3.14159265358979323846
#define paa pair<int, char>
#define mp make_pair
#define pb push_back
#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};
using namespace std;
class pa3 {
public:
  int x, y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  int x;
  int y, z, w;
  pa4(int x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }

  bool operator!=(const pa4 &p) const {
    return !(x == p.x && y == p.y && z == p.z && w == p.w);
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator>(const pa2 &p) const { return x != p.x ? x > p.x : y > p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

#define ppa pair<int, pas>
class Point {
public:
  double x, y;
  Point(double x = 0, double y = 0) : x(x), y(y) {}
  Point operator+(Point p) { return Point(x + p.x, y + p.y); }
  Point operator-(Point p) { return Point(x - p.x, y - p.y); }
  Point operator*(double a) { return Point(x * a, y * a); }
  Point operator/(double a) { return Point(x / a, y / a); }
  double absv() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
  bool operator<(const Point &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const Point &p) const {
    return fabs(x - p.x) < EPS && fabs(y - p.y) < EPS;
  }
};
typedef Point Vector;
#define pl pair<int, pas>
struct Segment {
  Point p1, p2;
};
double dot(Vector a, Vector b) { return a.x * b.x + a.y * b.y; }
double cross(Vector a, Vector b) { return a.x * b.y - a.y * b.x; }

bool parareru(Point a, Point b, Point c, Point d) {
  //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
  return abs(cross(a - b, d - c)) < EPS;
}
double distance_ls_p(Point a, Point b, Point c) {
  if (dot(b - a, c - a) < EPS)
    return (c - a).absv();
  if (dot(a - b, c - b) < EPS)
    return (c - b).absv();
  return abs(cross(b - a, c - a)) / (b - a).absv();
}
bool is_intersected_ls(Segment a, Segment b) {
  if (a.p1 == b.p1 || a.p2 == b.p1 || a.p1 == b.p2 || a.p2 == b.p2)
    return false;
  if (parareru((a.p2), (a.p1), (a.p1), (b.p2)) &&
      parareru((a.p2), (a.p1), (a.p1), (b.p1))) {
    //		cout<<"sss"<<endl;
    if (dot(a.p1 - b.p1, a.p1 - b.p2) < EPS)
      return true;
    if (dot(a.p2 - b.p1, a.p2 - b.p2) < EPS)
      return true;
    if (dot(a.p1 - b.p1, a.p2 - b.p1) < EPS)
      return true;
    if (dot(a.p1 - b.p2, a.p2 - b.p2) < EPS)
      return true;
    return false;
  } else
    return (cross(a.p2 - a.p1, b.p1 - a.p1) * cross(a.p2 - a.p1, b.p2 - a.p1) <
            EPS) &&
           (cross(b.p2 - b.p1, a.p1 - b.p1) * cross(b.p2 - b.p1, a.p2 - b.p1) <
            EPS);
}

double segment_dis(Segment a, Segment b) {
  if (is_intersected_ls(a, b))
    return 0;
  double r = distance_ls_p(a.p1, a.p2, b.p1);
  r = min(r, distance_ls_p(a.p1, a.p2, b.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p1));
  return r;
}
Point intersection_ls(Segment a, Segment b) {
  Point ba = b.p2 - b.p1;
  double d1 = abs(cross(ba, a.p1 - b.p1));
  double d2 = abs(cross(ba, a.p2 - b.p1));
  double t = d1 / (d1 + d2);

  return a.p1 + (a.p2 - a.p1) * t;
}

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

double distans(double x1, double y1, double x2, double y2) {
  double rr = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  return sqrt(rr);
}
int mod;
int pr[2010];
int inv[2010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1 % warukazu;
  if (rr == 1)
    return wa % warukazu;
  if (rr % 2 == 1)
    return (beki(wa, rr - 1, warukazu) * wa) % warukazu;
  int zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}
/*
double bekid(double w,int r){
if(r==0) return 1.0;
if(r==1) return w;
if(r%2) return bekid(w,r-1)*w;
double f=bekid(w,r/2);
return f*f;
}*/
/*
                    int comb(int nn,int rr){
                            int r=pr[nn]*inv[rr];
                            r%=mod;
                            r*=inv[nn-rr];
                            r%=mod;
                            return r;
                    }
  */
void gya(int ert) {
  pr[0] = 1;
  for (int i = 1; i < ert; i++) {
    pr[i] = (pr[i - 1] * i) % mod;
  }
  for (int i = 0; i < ert; i++)
    inv[i] = beki(pr[i], mod - 2, mod);
}

//   cin.tie(0);
//	ios::sync_with_stdio(false);
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//----------------kokomade tenpure------------

double a[40020], b[40020], c[40020];
int n;

vector<pair<pal, pal>> vv;

vector<pair<double, int>> ve;
int memo[400030];

struct segsum {
  //       1
  //   2        3
  // 4   5   6    7

private:
public:
  // (1<<15)=32768
  // 1<<16 = 65536
  // 1<<17 = 131072
  // 1<<18 = 262144

  int cor = (1 << 16);

  vector<int> vec;

  void shoki1() { vec.resize(2 * cor + 3, 0); }
  void shoki2() {
    for (int i = cor - 1; i > 0; i--)
      vec[i] = vec[2 * i] + vec[2 * i + 1];
  }
  void clear() {

    for (int i = 0; i < (int)vec.size(); i++)
      vec[i] = 0;
  }
  void updadd(int x, int w) {
    // x 項目に w加算
    x += cor;
    vec[x] += w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }

  void updchan(int x, int w) {
    // x項目をwに変更
    x += cor;
    vec[x] = w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }
  // [a,b)
  // k-th node
  // k no kukanha [l,r)
  int sum(int a, int b, int k = 1, int l = 0, int r = -10) {
    if (r < 0)
      r = cor;

    //	cout<<a<<" "<<b<<" "<<k<<" "<<l<<" "<<r<<endl;

    if (a <= l && r <= b) {
      return vec[k];
    }
    if (r <= a || b <= l) {
      return 0;
    }

    int v1 = sum(a, b, k * 2, l, (l + r) / 2),
        v2 = sum(a, b, k * 2 + 1, (l + r) / 2, r);
    return v1 + v2;
  }
};
segsum ss;
int tentou() {
  for (int i = 0; i < ss.vec.size(); i++)
    ss.vec[i] = 0;
  int ans = 0;
  for (int i = n - 1; i >= 0; i--) {
    ans += ss.sum(0, memo[i]);
    ss.updadd(memo[i], 1);
  }
  return ans;
}

int ch(double x) {
  ve.clear();
  for (int i = 0; i < n; i++) {
    ve.pb(mp((c[i] - a[i] * x) / b[i], i));
  }
  sort(ve.begin(), ve.end());
  for (int i = 0; i < n; i++)
    memo[i] = ve[i].second;
  int g = tentou();
  // cout<<x<<" "<<g<<endl;
  return g;
}

double solve() {
  vv.clear();
  for (int i = 0; i < n; i++)
    vv.pb(mp(mp(a[i] / b[i], a[i]), mp(b[i], c[i])));
  sort(vv.begin(), vv.end());
  for (int i = 0; i < n; i++) {
    a[i] = vv[i].first.second;
    b[i] = vv[i].second.first;
    c[i] = vv[i].second.second;
  }
  int zen = n * (n - 1) / 2;
  int han = (zen + 1) / 2;
  double ue = 1000000000.0;
  double si = -ue, me;
  for (int i = 0; i < 600; i++) {
    me = (ue + si) / 2.0;
    if (ch(me) < han)
      si = me;
    else
      ue = me;
  }
  return me;
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n;
  ss.shoki1();
  for (int i = 0; i < n; i++)
    cin >> a[i] >> b[i] >> c[i];

  double xans = solve();

  for (int i = 0; i < n; i++)
    swap(a[i], b[i]);
  double yans = solve();
  printf("%.10lf %.10lf\n", xans, yans);
  return 0;
}

Fixed submission:
#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <string>
#include <vector>
//    #include <boost/multiprecision/cpp_int.hpp>
#include <functional>
#define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, double>
#define ppap pair<pa, int>
#define PI 3.14159265358979323846
#define paa pair<int, char>
#define mp make_pair
#define pb push_back
#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};
using namespace std;
class pa3 {
public:
  int x, y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  int x;
  int y, z, w;
  pa4(int x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }

  bool operator!=(const pa4 &p) const {
    return !(x == p.x && y == p.y && z == p.z && w == p.w);
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator>(const pa2 &p) const { return x != p.x ? x > p.x : y > p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

#define ppa pair<int, pas>
class Point {
public:
  double x, y;
  Point(double x = 0, double y = 0) : x(x), y(y) {}
  Point operator+(Point p) { return Point(x + p.x, y + p.y); }
  Point operator-(Point p) { return Point(x - p.x, y - p.y); }
  Point operator*(double a) { return Point(x * a, y * a); }
  Point operator/(double a) { return Point(x / a, y / a); }
  double absv() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
  bool operator<(const Point &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const Point &p) const {
    return fabs(x - p.x) < EPS && fabs(y - p.y) < EPS;
  }
};
typedef Point Vector;
#define pl pair<int, pas>
struct Segment {
  Point p1, p2;
};
double dot(Vector a, Vector b) { return a.x * b.x + a.y * b.y; }
double cross(Vector a, Vector b) { return a.x * b.y - a.y * b.x; }

bool parareru(Point a, Point b, Point c, Point d) {
  //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
  return abs(cross(a - b, d - c)) < EPS;
}
double distance_ls_p(Point a, Point b, Point c) {
  if (dot(b - a, c - a) < EPS)
    return (c - a).absv();
  if (dot(a - b, c - b) < EPS)
    return (c - b).absv();
  return abs(cross(b - a, c - a)) / (b - a).absv();
}
bool is_intersected_ls(Segment a, Segment b) {
  if (a.p1 == b.p1 || a.p2 == b.p1 || a.p1 == b.p2 || a.p2 == b.p2)
    return false;
  if (parareru((a.p2), (a.p1), (a.p1), (b.p2)) &&
      parareru((a.p2), (a.p1), (a.p1), (b.p1))) {
    //		cout<<"sss"<<endl;
    if (dot(a.p1 - b.p1, a.p1 - b.p2) < EPS)
      return true;
    if (dot(a.p2 - b.p1, a.p2 - b.p2) < EPS)
      return true;
    if (dot(a.p1 - b.p1, a.p2 - b.p1) < EPS)
      return true;
    if (dot(a.p1 - b.p2, a.p2 - b.p2) < EPS)
      return true;
    return false;
  } else
    return (cross(a.p2 - a.p1, b.p1 - a.p1) * cross(a.p2 - a.p1, b.p2 - a.p1) <
            EPS) &&
           (cross(b.p2 - b.p1, a.p1 - b.p1) * cross(b.p2 - b.p1, a.p2 - b.p1) <
            EPS);
}

double segment_dis(Segment a, Segment b) {
  if (is_intersected_ls(a, b))
    return 0;
  double r = distance_ls_p(a.p1, a.p2, b.p1);
  r = min(r, distance_ls_p(a.p1, a.p2, b.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p1));
  return r;
}
Point intersection_ls(Segment a, Segment b) {
  Point ba = b.p2 - b.p1;
  double d1 = abs(cross(ba, a.p1 - b.p1));
  double d2 = abs(cross(ba, a.p2 - b.p1));
  double t = d1 / (d1 + d2);

  return a.p1 + (a.p2 - a.p1) * t;
}

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

double distans(double x1, double y1, double x2, double y2) {
  double rr = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  return sqrt(rr);
}
int mod;
int pr[2010];
int inv[2010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1 % warukazu;
  if (rr == 1)
    return wa % warukazu;
  if (rr % 2 == 1)
    return (beki(wa, rr - 1, warukazu) * wa) % warukazu;
  int zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}
/*
double bekid(double w,int r){
if(r==0) return 1.0;
if(r==1) return w;
if(r%2) return bekid(w,r-1)*w;
double f=bekid(w,r/2);
return f*f;
}*/
/*
                    int comb(int nn,int rr){
                            int r=pr[nn]*inv[rr];
                            r%=mod;
                            r*=inv[nn-rr];
                            r%=mod;
                            return r;
                    }
  */
void gya(int ert) {
  pr[0] = 1;
  for (int i = 1; i < ert; i++) {
    pr[i] = (pr[i - 1] * i) % mod;
  }
  for (int i = 0; i < ert; i++)
    inv[i] = beki(pr[i], mod - 2, mod);
}

//   cin.tie(0);
//	ios::sync_with_stdio(false);
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//----------------kokomade tenpure------------

double a[40020], b[40020], c[40020];
int n;

vector<pair<pal, pal>> vv;

vector<pair<double, int>> ve;
int memo[400030];

struct segsum {
  //       1
  //   2        3
  // 4   5   6    7

private:
public:
  // (1<<15)=32768
  // 1<<16 = 65536
  // 1<<17 = 131072
  // 1<<18 = 262144

  int cor = (1 << 16);

  vector<int> vec;

  void shoki1() { vec.resize(2 * cor + 3, 0); }
  void shoki2() {
    for (int i = cor - 1; i > 0; i--)
      vec[i] = vec[2 * i] + vec[2 * i + 1];
  }
  void clear() {

    for (int i = 0; i < (int)vec.size(); i++)
      vec[i] = 0;
  }
  void updadd(int x, int w) {
    // x 項目に w加算
    x += cor;
    vec[x] += w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }

  void updchan(int x, int w) {
    // x項目をwに変更
    x += cor;
    vec[x] = w;
    while (1) {
      x /= 2;
      if (x == 0)
        break;
      vec[x] = vec[2 * x] + vec[2 * x + 1];
    }
  }
  // [a,b)
  // k-th node
  // k no kukanha [l,r)
  int sum(int a, int b, int k = 1, int l = 0, int r = -10) {
    if (r < 0)
      r = cor;

    //	cout<<a<<" "<<b<<" "<<k<<" "<<l<<" "<<r<<endl;

    if (a <= l && r <= b) {
      return vec[k];
    }
    if (r <= a || b <= l) {
      return 0;
    }

    int v1 = sum(a, b, k * 2, l, (l + r) / 2),
        v2 = sum(a, b, k * 2 + 1, (l + r) / 2, r);
    return v1 + v2;
  }
};
segsum ss;
int tentou() {
  for (int i = 0; i < ss.vec.size(); i++)
    ss.vec[i] = 0;
  int ans = 0;
  for (int i = n - 1; i >= 0; i--) {
    ans += ss.sum(0, memo[i]);
    ss.updadd(memo[i], 1);
  }
  return ans;
}

int ch(double x) {
  ve.clear();
  for (int i = 0; i < n; i++) {
    ve.pb(mp((c[i] - a[i] * x) / b[i], i));
  }
  sort(ve.begin(), ve.end());
  for (int i = 0; i < n; i++)
    memo[i] = ve[i].second;
  int g = tentou();
  // cout<<x<<" "<<g<<endl;
  return g;
}

double solve() {
  vv.clear();
  for (int i = 0; i < n; i++)
    vv.pb(mp(mp(a[i] / b[i], a[i]), mp(b[i], c[i])));
  sort(vv.begin(), vv.end());
  for (int i = 0; i < n; i++) {
    a[i] = vv[i].first.second;
    b[i] = vv[i].second.first;
    c[i] = vv[i].second.second;
  }
  int zen = n * (n - 1) / 2;
  int han = (zen + 1) / 2;
  double ue = 1000000000.0;
  double si = -ue, me;
  for (int i = 0; i < 100; i++) {
    me = (ue + si) / 2.0;
    if (ch(me) < han)
      si = me;
    else
      ue = me;
  }
  return me;
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n;
  ss.shoki1();
  for (int i = 0; i < n; i++)
    cin >> a[i] >> b[i] >> c[i];

  double xans = solve();

  for (int i = 0; i < n; i++)
    swap(a[i], b[i]);
  double yans = solve();
  printf("%.10lf %.10lf\n", xans, yans);
  return 0;
}