제출 #501773

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
501773		chenwz	Mobile (BOI12_mobile)	C++11	100 / 100	361 ms	27392 KiB

mobile

// BalticOI2012 - Mobile
#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define _for(i, a, b) for (int i = (a); i < (int)(b); ++i)
const int NN = 1e6 + 4;
int X[NN], Y[NN];
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  int N, L;
  cin >> N >> L;
  // scanf("%d%d", &N, &L);
  for (int i = 0; i < N; i++)
    cin >> X[i] >> Y[i];  // scanf("%d%d", X + i, Y + i);
  double l = 1, r = 1.5e9;
  while (r - l > 1e-3) {
    double m = (l + r) / 2, curr = 0;
    for (int i = 0; i < N; i++) {
      double y = Y[i], delta = sqrt(m * m - y * y), a = X[i] - delta,
             b = X[i] + delta;
      if (a <= curr) curr = max(curr, b);
      if (curr >= L) break;
    }
    (curr >= L ? r : l) = m;
  }
  printf("%.4lf\n", l);
  return 0;
}
// 499716 Mobile (BOI12_mobile) C++11 100 / 100 405ms  27384KB

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