Submission #570481

#	Time	Username	Problem	Language	Result	Execution time	Memory
570481		lam	Mobile (BOI12_mobile)	C++14	50 / 100	43 ms	3788 KiB

mobile

#include <bits/stdc++.h>
#define int long long
#define maxn 100010
using namespace std;
int n,L;
pair<int,int> a[maxn];
typedef long double ld;
const ld eps=1e-3;
bool cmp(pair<ld,ld> x, pair<ld,ld> y)
{
    if (x.second!=y.second) return x.second<y.second;
    return x.first<y.first;
}
bool check(ld val)
{
    vector <pair<ld,ld>> b;
    b.clear();
    val*=val;
    ld curr=0.0;
    for (int i=1; i<=n; i++)
    {
        ld temp=a[i].second;
        temp=1.0*temp*temp;
        if (temp>val) continue;
        temp=val-temp;
        temp=1.0*sqrt(temp);
        ld l=a[i].first-temp;
        ld r=a[i].first+temp;
        if (l<=curr) curr=max(curr,r);
    }
    return curr>=L;
}
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    cin>>n>>L;
    for (int i=1; i<=n; i++)
    {
        cin>>a[i].first>>a[i].second;
    }
    ld l=0.0;
    ld r=2*1e9;
    ld ans=-1;
    while (r-l>eps)
    {
        ld mid=l+(r-l)/2;
        if (check(mid))
        {
            r=mid;
        }
        else
            l=mid;
    }
    cout<<fixed<<setprecision(4)<<l;
}

Compilation message (stderr)

mobile.cpp: In function 'int main()':
mobile.cpp:44:8: warning: unused variable 'ans' [-Wunused-variable]
   44 |     ld ans=-1;
      |        ^~~

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