Problem p00936 (C++)

Buggy submission (status: Time Limit Exceeded):
//  aoj-VolumeICPCOOC2015-B  / 2015-11-30
#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef ll int__;
#define rep(i, j) for (int__ i = 0; i < (int__)(j); i++)
#define repeat(i, j, k) for (int__ i = (j); i < (int__)(k); i++)
#define all(v) v.begin(), v.end()

template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  rep(i, v.size()) os << v[i] << (i != v.size() - 1 ? " " : "");
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  rep(i, v.size()) is >> v[i];
  return is;
}

#ifdef DEBUG
void debug() { cerr << " : Debug" << endl; }
#endif
template <class F, class... R> void debug(const F &car, const R &...cdr) {
#ifdef DEBUG
  cerr << car << " ";
  debug(cdr...);
#endif
}

const double EPS = 1e-8;

struct Point {
  double x, y;
  Point() : x(0), y(0) {}
  Point(double x, double y) : x(x), y(y){};
  bool operator==(const Point &a) const { return x == a.x && y == a.y; }
  Point operator-(const Point &p) const { return Point(x - p.x, y - p.y); }
};
istream &operator>>(istream &is, Point &p) { return is >> p.x >> p.y; }
ostream &operator<<(ostream &os, const Point &p) {
  return os << "(" << p.x << "," << p.y << ")";
}

double dot(const Point &a, const Point &b) { return a.x * b.x + a.y * b.y; }
double cross(const Point &a, const Point &b) { return a.x * b.y - a.y * b.x; }
double norm(const Point &a) { return sqrt(dot(a, a)); }
double distance(const Point &a, const Point &b) { return norm(a - b); }

bool check(vector<Point> &P, vector<int> &R, Point &np, int nr) {
  rep(i, P.size()) {
    if (distance(P[i], np) - (R[i] + nr) < 0.0)
      return false;
  }
  return true;
}

bool solve() {
  int n;
  cin >> n;
  vector<int> R(n);
  cin >> R;
  vector<Point> P;
  for (int r : R) {
    double l = P.size() > 0 ? max(P.back().x, (double)r) : r;
    double h = 1e10;
    while (h - l > 1e-9) {
      double m = (l + h) / 2;
      Point p = Point(m, r);
      if (check(P, R, p, r))
        h = m;
      else
        l = m;
    }
    P.push_back(Point(h, r));
  }
  debug(P);
  double ans = 0;
  rep(i, P.size()) ans = max(ans, P[i].x + R[i]);
  printf("%.10f\n", ans);
  return false;
}

int main() {
  ios::sync_with_stdio(false);
  while (solve())
    ;
  return 0;
}

Fixed submission:
//  aoj-VolumeICPCOOC2015-B  / 2015-11-30
#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef ll int__;
#define rep(i, j) for (int__ i = 0; i < (int__)(j); i++)
#define repeat(i, j, k) for (int__ i = (j); i < (int__)(k); i++)
#define all(v) v.begin(), v.end()

template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  rep(i, v.size()) os << v[i] << (i != v.size() - 1 ? " " : "");
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  rep(i, v.size()) is >> v[i];
  return is;
}

#ifdef DEBUG
void debug() { cerr << " : Debug" << endl; }
#endif
template <class F, class... R> void debug(const F &car, const R &...cdr) {
#ifdef DEBUG
  cerr << car << " ";
  debug(cdr...);
#endif
}

const double EPS = 1e-8;

struct Point {
  double x, y;
  Point() : x(0), y(0) {}
  Point(double x, double y) : x(x), y(y){};
  bool operator==(const Point &a) const { return x == a.x && y == a.y; }
  Point operator-(const Point &p) const { return Point(x - p.x, y - p.y); }
};
istream &operator>>(istream &is, Point &p) { return is >> p.x >> p.y; }
ostream &operator<<(ostream &os, const Point &p) {
  return os << "(" << p.x << "," << p.y << ")";
}

double dot(const Point &a, const Point &b) { return a.x * b.x + a.y * b.y; }
double cross(const Point &a, const Point &b) { return a.x * b.y - a.y * b.x; }
double norm(const Point &a) { return sqrt(dot(a, a)); }
double distance(const Point &a, const Point &b) { return norm(a - b); }

bool check(vector<Point> &P, vector<int> &R, Point &np, int nr) {
  rep(i, P.size()) {
    if (distance(P[i], np) - (R[i] + nr) < 0.0)
      return false;
  }
  return true;
}

bool solve() {
  int n;
  cin >> n;
  vector<int> R(n);
  cin >> R;
  vector<Point> P;
  for (int r : R) {
    double l = P.size() > 0 ? max(P.back().x, (double)r) : r;
    double h = 1e10;
    while (h - l > 1e-8) {
      double m = (l + h) / 2;
      Point p = Point(m, r);
      if (check(P, R, p, r))
        h = m;
      else
        l = m;
    }
    P.push_back(Point(h, r));
  }
  debug(P);
  double ans = 0;
  rep(i, P.size()) ans = max(ans, P[i].x + R[i]);
  printf("%.10f\n", ans);
  return false;
}

int main() {
  ios::sync_with_stdio(false);
  while (solve())
    ;
  return 0;
}