Submission #499716

#	Time	Username	Problem	Language	Result	Execution time	Memory
499716		chenwz	Mobile (BOI12_mobile)	C++11	100 / 100	405 ms	27384 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() {
  int N, L;
  scanf("%d%d", &N, &L);
  _for(i, 0, N) 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(i, 0, N) {
      double x = X[i], y = Y[i], delta = sqrt(m * m - y * y), a = x - delta,
             b = x + delta;
      if (a <= curr) curr = max(curr, b);
      if(curr >= L) break;
    }
    (curr >= L ? r : l) = m;
  }
  printf("%.4lf\n", l);
  return 0;
}

Compilation message (stderr)

mobile.cpp: In function 'int main()':
mobile.cpp:10:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |   scanf("%d%d", &N, &L);
      |   ~~~~~^~~~~~~~~~~~~~~~
mobile.cpp:11:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |   _for(i, 0, N) scanf("%d%d", X + i, Y + i);
      |                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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