#pragma GCC optimize ("Ofast,fast-math,inline")
#pragma GCC target ("Ofast,fast-math,avx2")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <typename K> using hset = gp_hash_table<K, null_type>;
template <typename K, typename V> using hmap = gp_hash_table<K, V>;
using namespace std;
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define eb emplace_back
#define smax(x, y) (x = max(x, y))
#define smin(x, y) (x = min(x, y))
using ld = long double;
using ll = long long;
template <typename T>
using vv = vector<vector<T>>;
using vi = vector<int>;
using ii = array<int, 2>;
using vii = vector<ii>;
using vvi = vv<int>;
using vll = vector<ll>;
using l2 = array<int, 2>;
using vl2 = vector<l2>;
using vvll = vv<ll>;
template <typename T>
using minq = priority_queue<T, vector<T>, greater<T>>;
template <typename T>
using maxq = priority_queue<T>;
const ll M = 1000000007;
#ifndef REFERENCE_DISCRETE_BINARY_SEARCH_H
#define REFERENCE_DISCRETE_BINARY_SEARCH_H
#include <iostream>
#include <functional>
template<typename IN>
IN discrete_binary_search(function<bool(IN)> predicate, IN low = 0, IN high = numeric_limits<IN>::max()) {
while (fabs(high - low) > 1e-4) {
IN middle = low + (high - low) / 2; // todo std::midpoint in cpp 2020
if (predicate(middle))
high = middle;
else low = middle;
}
return low;
}
#endif //REFERENCE_DISCRETE_BINARY_SEARCH_H
inline bool a_contains_b(array<ld, 2> a, array<ld, 2> b) {
return a[0] <= b[0] && b[1] <= a[1];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, l;
cin >> n >> l;
vll x(n), y(n);
for (int i = 0; i < n; ++i) {
cin >> x[i] >> y[i];
}
cout << fixed << setprecision(4) << discrete_binary_search<ld>([&](ld d) -> bool {
// is there a point with min distance > d
// equivalently, is every point within distance d
vector<array<ld, 2>> intervals;
intervals.reserve(n);
// add to intervals
for (int i = 0; i < n; ++i) {
if (abs(y[i]) > d) continue;
ld dx = sqrt(d * d - y[i] * y[i]);
// get rid of nested intervals
ld s1 = x[i] - dx, e1 = x[i] + dx;
// can merge in place
while (!intervals.empty()) {
auto & [s2, e2] = intervals.back();
if (max(s1, s2) <= min(e1, e2)) {
smin(s1, s2);
smax(e1, e2);
intervals.pop_back();
} else break;
}
intervals.pb({s1, e1});
}
// check interval spans whole highway
array<ld, 2> highway{0, (ld) l};
for (auto interval : intervals) {
if (a_contains_b(interval, highway)) return true;
}
return false;
}, 0, sqrt(1e18 + 4 * 1e18 + 1e10)) << '\n';
}
Compilation message
cc1plus: error: attribute 'Ofast' argument 'target' is unknown
cc1plus: error: attribute 'fast-math' argument 'target' is unknown
