Submission #1245755

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245755		tredsused70	Mobile (BOI12_mobile)	C++20	100 / 100	240 ms	8264 KiB

mobile

//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx,avx2")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,avx,avx2")
//#pragma GCC optimize("trapv")
#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define mpr make_pair
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const int nmax = 1000011, mod = 1000000007, inf = 2000010000, key = 200003, lg = 20, block = 300;
const ll infll = 4000000000000000000;
const ld eps = 1e-9;

bool check(vector<array<int, 2>> &vc, ld d, int e) {
    ld cur = 0, l, r;
    for(int i = 0; i < vc.size(); i++) {
        if(abs(vc[i][1]) >= d)
            continue;
        l = vc[i][0] - sqrt(d * d - 1ll * vc[i][1] * vc[i][1]);
        r = vc[i][0] + sqrt(d * d - 1ll * vc[i][1] * vc[i][1]);
        //cout << i << " " << d << cur << " " << l << " " << r << "\n";
        if(l <= cur) {
            if(r >= e)
                return 1;
            cur = max(cur, r);
        }
        else {
            if(vc[i][0] > cur + d)
                return 0;
        }
    }
    //cout << "\n\n";
    return (cur >= e);
}

void solve()
{
    int n, ln;
    cin >> n >> ln;
    vector<array<int, 2>> vc(n);
    for(int i = 0; i < n; i++) {
        cin >> vc[i][0] >> vc[i][1];
    }
    sort(all(vc));
    ld l = 0, r = 3000000000;
    while(r - l > 0.0005) {
        ld m = (l + r) / 2;
        if(check(vc, m, ln))
            r = m;
        else
            l = m;
    }
    cout << fixed << setprecision(6) << r << "\n";
    return ;
}

int main()
{
    //freopen("balancing.in","r",stdin);
    //freopen("balancing.out","w",stdout);
    ios_base::sync_with_stdio(0);cin.tie(0);
    srand(8713);
    //init();
    int t = 1;
    //cin >> t;
    //int t_ = t;
    //t = rdi();
    while(t--) {
        //cout << "Case #" << t_ - t << ": ";
        solve();
    }
    //flush();
    return 0;
}

/*
6
1 1
1 3
1 5
1 7
1 9
1 11
*/

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
• Subtask 12: 5 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5