제출 #1349162

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1349162		hokhaiinn	Mobile (BOI12_mobile)	C++20	43 / 100	730 ms	31756 KiB

mobile

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;
using vvi = vector<vi>;
using str = string;
using vl = vector<ll>;
using vvl = vector<vl>;
using vp = vector<pii>;
using vs = vector<str>;
using ld = long double;
using si = set<int>;
using mii = map<int, int>;
#define st first
#define nd second
#define pb push_back
#define eb emplace_back
#define nn '\n'
#define ub upper_bound
#define lb lower_bound
#define LL_MAX LONG_LONG_MAX
#define LL_MIN LONG_LONG_MIN
#define it iterator

static const int _ = []() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();

bool check(const int & n, const ld& m, const vector<pair<ld, ld>>& t, const ld & d){
    ld l, r, ran;
    int i = 0;
    while (i < n && d * d < t[i].nd * t[i].nd){
        ++i;
    }
    if (i == n){
        return false;
    }
    ran = sqrt(d * d - t[i].nd * t[i].nd);
    l = t[i].st - ran;
    r = t[i].st + ran;
    stack<ld> gap;
    for (; i < n; ++i){
        if (d * d >= t[i].nd * t[i].nd){
            ran = sqrt(d * d - t[i].nd * t[i].nd);
            if (r >= 0 && t[i].st - ran > r){
                gap.push(r);
            }
            while (!gap.empty() && t[i].st - ran <= gap.top()){
                gap.pop();
            }
            l = min(l, t[i].st - ran);
            r = max(r, t[i].st + ran);
        }
    }
    return gap.empty() && r >= m && l <= 0;
}

int main(){
    int n;
    ld l;
    cin >> n >> l;
    fixed(cout);
    vector<pair<ld, ld>> t(n);
    for (int i = 0; i < n; ++i){
        cin >> t[i].st >> t[i].nd;
    }
    ld lo, hi, mid;
    lo = 0;
    hi = 3e9;
    while (lo < hi - 1e-6){
        mid = (lo + hi) / 2;
        if (check(n, l, t, mid)){
            hi = mid;
        } else {
            lo = mid + 1e-6;
        }
    }
    cout << setprecision(6) << lo;
    return 0;
}

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