Submission #115200

#	Time	Username	Problem	Language	Result	Execution time	Memory
115200		luciocf	Mobile (BOI12_mobile)	C++14	50 / 100	1083 ms	48620 KiB

mobile

#include <bits/stdc++.h>

#pragma GCC optimize("Ofast")
 
#define ff first
#define ss second
 
using namespace std;
 
const int maxn = 1e6+10;
const double inf = 1e9+10;
 
typedef pair<double, double> pt;
 
int n;
double L;
 
pt p[maxn];
 
double dist(pt a, pt b)
{
	double d1 = a.ff-b.ff;
	double d2 = a.ss-b.ss;
 
	return sqrt(d1*d1 + d2*d2);
}
 
bool ok(double K)
{
	vector<pt> V;
 
	for (int i = 1; i <= n; i++)
	{
		double x = p[i].ff, y = p[i].ss;
 
		if (K*K < y*y)
			continue;
 
		double delta = sqrt(K*K - y*y);
 
		double x1 = x-delta, x2 = x+delta;

		V.push_back({x1, x2});
	}

	sort(V.begin(), V.end());
 
	double r = 0.00;

	for (int i = 0; i < V.size(); i++)
		if (V[i].ff < r)
			r = max(r, V[i].ss);

	return (r <= L);
}
 
double busca(void)
{
	double ini = 0.00, fim = inf, ans = 0.00;
 
	for (int i = 1; i <= 60; i++)
	{
		double mid = (ini+fim)/2.00;
 
		if (ok(mid)) ans = mid, ini = mid;
		else fim = mid;
	}
 
	return ans;
}
 
int main(void)
{
	scanf("%d %lf\n", &n, &L);
 
	for (int i = 1; i <= n; i++)
		scanf("%lf %lf", &p[i].ff, &p[i].ss);
 
	printf("%.9lf\n", busca());
}

Compilation message (stderr)

mobile.cpp: In function 'bool ok(double)':
mobile.cpp:50:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < V.size(); i++)
                  ~~^~~~~~~~~~
mobile.cpp: In function 'int main()':
mobile.cpp:74:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %lf\n", &n, &L);
  ~~~~~^~~~~~~~~~~~~~~~~~~~
mobile.cpp:77:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lf %lf", &p[i].ff, &p[i].ss);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
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