This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
/*
binary search on the answer
to test a value x, for all the circles come up with ranges of the line that is covered if the circle has a radius x
find the minimum value x s.t. the whole line is covered
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define For(i, a, b) for(int i=a; i<b; i++)
#define ffi For(i, 0, N)
#define ffj For(j, 0, N)
#define ffa ffi ffj
#define s <<" "<<
#define c <<" : "<<
#define w cout
#define e endl//"\n"
#define pb push_back
#define mp make_pair
#define a first
#define b second
#define int ll
#define double long double
const int MAXN=1000000, INF=1000000000000000000;
///500,000,000
int N, L;
pair<double, double> pts[MAXN], rng[MAXN];
bool full(double rr) {
/// make the ranges
ffi {
int x = pts[i].a, y = pts[i].b;
if (y*y > rr*rr) {rng[i] = mp(0, 0); continue;}
double l = x - sqrt(rr*rr-y*y); double r = x + sqrt(rr*rr-y*y);
l = max(l, (double) 0); l = min(l, (double)L);
r = max(r, (double) 0); r = min(r, (double)L);
rng[i] = mp(l, r);
}
//exit(0);
sort(rng, rng+N);
//w<< rr<<e; ffi w<< rng[i].a s rng[i].b<<e;
/// see if the whole range is covered
double far = 0;
ffi {
if (rng[i].a > far) return false;
far = max(far, rng[i].b);
}
return far >=L;
}
main() {
//ifstream cin("test.in");
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> L;
double a = 0, b = 2236067978;
ffi {
cin >> pts[i].a >> pts[i].b;
double x = pts[i].a, y = pts[i].b;
double use1 = sqrt(x*x+y*y);
double use2 = sqrt((x-L)*(x-L)+y*y);
b = min(b, max(use1, use2));
a = max(a, min(use1, use2));
}
while (b-a > .001) {
double mid = (a+b)/2;
if (full(mid)) b = mid;
else a = mid;
}
w<< fixed << setprecision(4) <<a<<e;
}
Compilation message (stderr)
mobile.cpp:50:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
main() {
^
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