Submission #1148897

#	Time	Username	Problem	Language	Result	Execution time	Memory
1148897		ByeWorld	Mobile (BOI12_mobile)	C++20	0 / 100	1096 ms	48180 KiB

mobile

#include <bits/stdc++.h>
#define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<char,char> pcc;
typedef pair<pii,int> ipii;
typedef pair<pii,pii> ipiii;
const int MAXN = 5e5+10;
const int SQRT = 300;
const int MAXA = 50;
const int LOG = 20;
const int INF = 1e9+10;
const ld EPS = 1e-5;
const int MOD = 998244353;
int sum(int a, int b){ return (a+b)%MOD; }
void chsum(int &a, int b){ a = (a+b)%MOD; }
void chsub(int &a, int b){ a = (a+MOD-b)%MOD; }
int mul(int a, int b){ return (a*b)%MOD; }
void chmul(int &a, int b){ a = (a*b)%MOD; }
void chmn(int &a, int b){ a = min(a, b); }
void chmx(int &a, int b){ a = max(a, b); }

int n;
ld len, x[MAXN], y[MAXN];

bool cek(ld mid){
    vector<pair<ld,ld>> vec;
    for(int i=1; i<=n; i++){ 
        if(abs(y[i]) >= mid) continue;
        ld dis = sqrt(mid*mid - y[i]*y[i]);
        vec.pb({x[i]-dis+EPS, x[i]+dis-EPS});
    }
    sort(vec.begin(), vec.end());
    ld mx = 0;
    for(auto [p, q] : vec){
        // cout << p << ' '<<q << "pq\n";
        if(p > q) continue;
        if(q<0) continue;
        if(mx < p) return 0;
        mx = q;
    }
    return (mx >= len);
}
signed main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin>>n>>len;
    for(int i=1; i<=n; i++) cin>>x[i]>>y[i];
        // cout << cek(5) <<"cek\n";
    // return 0;
    ld l=0, r=INF, mid=0, cnt=0;
    while(r-l>=EPS){
        mid = (l+r)/2;
        if(cek(mid)) cnt = mid, r = mid;
        else l = mid;
    }
    cout << fixed << setprecision(4) << cnt << '\n';
}

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