Problem p02303 (C++) — buggy submission, verdict: Time Limit Exceeded

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

using namespace std;

#define eps 0.0000000001

struct vec {
  double x, y;
  void nextvec() {
    scanf("%lf %lf", &x, &y);
    return;
  }
  vec operator+(const vec &a) const { return (vec){x + a.x, y + a.y}; }
  vec operator-(const vec &a) const { return (vec){x - a.x, y - a.y}; }
  vec operator*(const double &k) const { return (vec){k * x, k * y}; }
  vec sca(double t) { return (vec){t * x, t * y}; }
  double dot(vec a) { return x * a.x + y * a.y; }
  double cross(vec a) { return x * a.y - y * a.x; }
  double norm() { return sqrt(x * x + y * y); }
  double norm2() { return x * x + y * y; }
};

bool xsort(vec qwe, vec rty) { return qwe.x < rty.x; }
bool ysort(vec qwe, vec rty) { return qwe.y < rty.y; }

vec pt[100000];
vec ytmp[100000];
vec ymerge[100000];
double ma = 100000000000.0;

double closestpair(int l, int r) {
  if (r - l <= 1)
    return ma;
  int m = l + (r - l) / 2;
  double xm = pt[m].x;
  double res = min(closestpair(l, m), closestpair(m, r));

  int hdmerge = 0, hdtmp = 0, lhd = l, rhd = m;
  vec now;
  for (;;) {
    if (lhd == m && rhd == r)
      break;
    else if (rhd == r)
      now = pt[lhd++];
    else if (lhd == m)
      now = pt[rhd++];
    else if (ysort(pt[lhd], pt[rhd]))
      now = pt[lhd++];
    else
      now = pt[rhd++];

    ymerge[hdmerge++] = now;
    if (abs(now.x - xm) <= res + eps) {
      ytmp[hdtmp++] = now;
      for (int i = hdtmp - 2; i >= 0; --i) {
        if (abs(ytmp[i].y - now.y) >= res - eps)
          break;
        res = min(res, (now - ytmp[i]).norm());
      }
    }
  }
  for (int i = l; i < r; ++i)
    pt[i] = ymerge[i - l];

  return res;
}

signed main(void) {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i)
    pt[i].nextvec();
  sort(pt, pt + n, xsort);
  printf("%.13lf\\n", closestpair(0, n));

  return 0;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;

#define PI 3.141592653589793238462643383279
#define mod 1000000007LL
#define rep(i, n) for (i = 0; i < n; ++i)
#define rep1(i, n) for (i = 1; i < n; ++i)
#define per(i, n) for (i = n - 1; i > -1; --i)
#define int(x)                                                                 \\
  int x;                                                                       \\
  scanf("%d", &x)
#define int2(x, y)                                                             \\
  int x, y;                                                                    \\
  scanf("%d%d", &x, &y)
#define int3(x, y, z)                                                          \\
  int x, y, z;                                                                 \\
  scanf("%d%d%d", &x, &y, &z)
#define int4(v, x, y, z)                                                       \\
  int v, x, y, z;                                                              \\
  scanf("%d%d%d%d", &v, &x, &y, &z)
#define int5(v, w, x, y, z)                                                    \\
  int v, w, x, y, z;                                                           \\
  scanf("%d%d%d%d%d", &v, &w, &x, &y, &z)
#define ll2(x, y)                                                              \\
  ll x, y;                                                                     \\
  cin >> x >> y;
#define scn(n, a) rep(i, n) cin >> a[i]
#define sc2n(n, a, b) rep(i, n) cin >> a[i] >> b[i]
#define pri(x) cout << (x) << "\\n"
#define pri2(x, y) cout << (x) << " " << (y) << "\\n"
#define pri3(x, y, z) cout << (x) << " " << (y) << " " << (z) << "\\n"
#define pb push_back
#define mp make_pair
#define all(a) (a).begin(), (a).end()
#define endl "\\n"
#define kabe puts("---------------------------")
#define kara puts("")
#define debug(x) cout << " --- " << (x) << "\\n"
#define debug2(x, y) cout << " --- " << (x) << " " << (y) << "\\n"
#define debug3(x, y, z)                                                        \\
  cout << " --- " << (x) << " " << (y) << " " << (z) << "\\n"
#define X first
#define Y second
#define eps 0.00000000001
#define prid(x) printf("%.15lf\\n", x)

struct vec {
  double x, y;
  void nextvec() {
    scanf("%lf %lf", &x, &y);
    return;
  }
  vec operator+(const vec &a) const { return (vec){x + a.x, y + a.y}; }
  vec operator-(const vec &a) const { return (vec){x - a.x, y - a.y}; }
  vec operator*(const double &k) const { return (vec){k * x, k * y}; }
  vec sca(double t) { return (vec){t * x, t * y}; }
  double dot(vec a) { return x * a.x + y * a.y; }
  double cross(vec a) { return x * a.y - y * a.x; }
  double norm() { return sqrt(x * x + y * y); }
  double norm2() { return x * x + y * y; }
};

bool xsort(vec qwe, vec rty) { return qwe.x < rty.x; }
bool ysort(vec qwe, vec rty) { return qwe.y < rty.y; }

vec pt[100000];
double ma = 100000000000.0;

vec ytmp[100000];
vec ymerge[100000];
double closestpair(int l, int r) {
  if (r - l <= 1)
    return ma;
  int m = l + (r - l) / 2;
  double xm = pt[m].x;
  double res = closestpair(l, m);
  res = min(res, closestpair(m, r));

  int hdmerge = 0, hdtmp = 0, lhd = l, rhd = m;
  vec now;
  for (;;) {
    if (lhd == m && rhd == r)
      break;
    else if (rhd == r)
      now = pt[lhd++];
    else if (lhd == m)
      now = pt[rhd++];
    else if (ysort(pt[lhd], pt[rhd]))
      now = pt[lhd++];
    else
      now = pt[rhd++];

    ymerge[hdmerge++] = now;
    if (now.x - xm <= res + eps) {
      ytmp[hdtmp++] = now;
      for (int i = hdtmp - 2; i >= 0; --i) {
        if (ytmp[i].y - now.y >= res - eps)
          break;
        res = min(res, (now - ytmp[i]).norm());
      }
    }
  }
  for (int i = l; i < r; ++i)
    pt[i] = ymerge[i - l];

  return res;
}

signed main(void) {
  int i, j;
  for (int testcase = 0; testcase >= 0; testcase++) {
    int(n);
    rep(i, n) pt[i].nextvec();
    sort(pt, pt + n, xsort);
    printf("%.13lf\\n", closestpair(0, n));

    /*/

    //*/
    break;
  }
  return 0;
}