Submission #906160

#	Time	Username	Problem	Language	Result	Execution time	Memory
906160		belgianbot	Mobile (BOI12_mobile)	C++14	100 / 100	346 ms	10584 KiB

mobile

#include <bits/stdc++.h>
#define pow(x, y) (double)(pow(x, y))
using namespace std;

struct coord{
	int x, y;
};

vector <coord> a;
int N, L;
/*double dis(int ax, ay, double ans) {
	return (double)(sqrt(pow(ay, 2) + pow(ax - ans, 2)));
}
double distance(int i, int j) {
	long long num = pow(a[i].y, 2) - pow(a[j].y, 2) - pow(a[j].x, 2) + pow(a[i].x, 2);
	long long den = 2 * (-a[j].x + a[i].x);
	
	if (den == 0) return sqrt(num);
	double frac = (double)(num) / (double)(den);
	
	return frac;
}*/
bool solve(double mid) {
	double right(0);
	for (int i(0); i < a.size(); i++) {
		if (abs(a[i].y) > mid) continue;
		double iLeft = (double)(a[i].x) - (double)(sqrt(mid * mid - double(a[i].y) * double(a[i].y)));
		double iRight = a[i].x + (a[i].x - iLeft);
		if (iLeft <= right) right = max(right,iRight);
	}
	return (right >= L);
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> N >> L;
	
	a.clear();
	int x, y; cin >> x >> y;
	a.push_back({x, y});
	for (int i(0); i < N - 1; i++) {
		int ax, ay;
		cin >> ax >> ay;
		if (ax == a[(int)(a.size() - 1)].x){
			if (abs(ay) < abs(a[(int)(a.size() - 1)].y)) {
				a[(int)(a.size() - 1)].y = ay;
			}
			else continue;
		}
		a.push_back({ax, ay});
	}
	double l(0), r(1e9);
	while (r - l > 0.0003) {
		double mid = l + (r - l) / 2;
		
		if (solve(mid)){
			 r = mid;
		 }
		else l = mid;
	}
	cout <<  setprecision(5) << fixed << l << '\n';
	return 0;
}

Compilation message (stderr)

mobile.cpp: In function 'bool solve(double)':
mobile.cpp:25:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<coord>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |  for (int i(0); i < a.size(); i++) {
      |                 ~~^~~~~~~~~~

• Subtask 1: 4 / 4
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