Submission #314063

#	Time	Username	Problem	Language	Result	Execution time	Memory
314063		shrek12357	Mobile (BOI12_mobile)	C++14	90 / 100	1037 ms	16128 KiB

mobile

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <climits>
#include <cmath>
#include <fstream>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define ll long long
//cin.tie(0); ios_base::sync_with_stdio(0); 

const int MAXN = 1e6 + 5;

double n, l;
vector<pair<double, double>> points(MAXN);

bool check(double mid) {
	double left = 0;
	for (int i = 0; i < points.size(); i++) {
		if (left >= l) {
			return true;
		}
		if (mid < points[i].second) {
			continue;
		}
		double temp = sqrt(mid*mid - points[i].second*points[i].second);
		if (temp + points[i].first <= left) {
			continue;
		}
		if (points[i].first - temp <= left) {
			left = points[i].first + temp, left;
		}
	}
	return left >= l;
}

int main() {
	cin.tie(0); ios_base::sync_with_stdio(0); 
	cin >> n >> l;
	for (int i = 0; i < n; i++) {
		double a, b;
		cin >> a >> b;
		points[i] = make_pair( a, b );
	}
	double lo = 0;
	double hi = 1e9;
	double ans = 1e10;
	while (hi - lo > 1e-3) {
		double mid = (lo + hi) / 2;
		if (check(mid)) {
			ans = min(ans, mid);
			hi = mid;
		}
		else {
			lo = mid;
		}
	}
	printf("%.7lf\n", ans);
}

Compilation message (stderr)

mobile.cpp: In function 'bool check(double)':
mobile.cpp:24:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |  for (int i = 0; i < points.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~
mobile.cpp:36:39: warning: right operand of comma operator has no effect [-Wunused-value]
   36 |    left = points[i].first + temp, left;
      |                                       ^

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