Submission #684257

#	Time	Username	Problem	Language	Result	Execution time	Memory
684257		ThisWasUnplanned	Mobile (BOI12_mobile)	C++17	0 / 100	689 ms	33480 KiB

mobile

/*
⡆⣐⢕⢕⢕⢕⢕⢕⢕⢕⠅⢗⢕⢕⢕⢕⢕⢕⢕⠕⠕⢕⢕⢕⢕⢕⢕⢕⢕⢕
⢐⢕⢕⢕⢕⢕⣕⢕⢕⠕⠁⢕⢕⢕⢕⢕⢕⢕⢕⠅⡄⢕⢕⢕⢕⢕⢕⢕⢕⢕
⢕⢕⢕⢕⢕⠅⢗⢕⠕⣠⠄⣗⢕⢕⠕⢕⢕⢕⠕⢠⣿⠐⢕⢕⢕⠑⢕⢕⠵⢕
⢕⢕⢕⢕⠁⢜⠕⢁⣴⣿⡇⢓⢕⢵⢐⢕⢕⠕⢁⣾⢿⣧⠑⢕⢕⠄⢑⢕⠅⢕
⢕⢕⠵⢁⠔⢁⣤⣤⣶⣶⣶⡐⣕⢽⠐⢕⠕⣡⣾⣶⣶⣶⣤⡁⢓⢕⠄⢑⢅⢑
⠍⣧⠄⣶⣾⣿⣿⣿⣿⣿⣿⣷⣔⢕⢄⢡⣾⣿⣿⣿⣿⣿⣿⣿⣦⡑⢕⢤⠱⢐
⢠⢕⠅⣾⣿⠋⢿⣿⣿⣿⠉⣿⣿⣷⣦⣶⣽⣿⣿⠈⣿⣿⣿⣿⠏⢹⣷⣷⡅⢐
⣔⢕⢥⢻⣿⡀⠈⠛⠛⠁⢠⣿⣿⣿⣿⣿⣿⣿⣿⡀⠈⠛⠛⠁⠄⣼⣿⣿⡇⢔
⢕⢕⢽⢸⢟⢟⢖⢖⢤⣶⡟⢻⣿⡿⠻⣿⣿⡟⢀⣿⣦⢤⢤⢔⢞⢿⢿⣿⠁⢕
⢕⢕⠅⣐⢕⢕⢕⢕⢕⣿⣿⡄⠛⢀⣦⠈⠛⢁⣼⣿⢗⢕⢕⢕⢕⢕⢕⡏⣘⢕
⢕⢕⠅⢓⣕⣕⣕⣕⣵⣿⣿⣿⣾⣿⣿⣿⣿⣿⣿⣿⣷⣕⢕⢕⢕⢕⡵⢀⢕⢕
⢑⢕⠃⡈⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⢃⢕⢕⢕
⣆⢕⠄⢱⣄⠛⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠿⢁⢕⢕⠕⢁
⣿⣦⡀⣿⣿⣷⣶⣬⣍⣛⣛⣛⡛⠿⠿⠿⠛⠛⢛⣛⣉⣭⣤⣂⢜⠕⢑⣡⣴⣿
*/
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long LL;
typedef long double LD;
#define MAX 100
#define pi acos(-1)
#define whatis(x) cout << #x << " is " << x << "\n";
#define all(x) x.begin(), x.end()
#define endl "\n"
#define DEB cout << "TESTING" NL
#define TESTS int test; cin>>test; for(int kase = 1 ; kase <= test ; kase++) solve(kase);
#define CASEOUT cout << "Case " << testcase << ": " << 
#define YESNO cout << (possible? "YES\n" : "NO\n");
// #define YES cout << "YES\n";
// #define NO cout << "NO\n";
#define int long long
#define pii pair<int,int>
 
int n;
LD l;
vector <pair <LD, LD>> towers;

LD distance(pair<LD, LD> a, pair<LD, LD> b)
{
    return (a.first - b.first) * (a.first - b.first) + (a.second - b.second) * (a.second - b.second);
}

bool check(LD val)
{
    LD ms = LDBL_MAX, me = LDBL_MAX;
    for(int i = 0 ; i < towers.size() ; i++)
    {
        ms = min(ms, distance({0,0}, towers[i]));
        me = min(me, distance({l,0}, towers[i]));
    }
    if(ms > val || me > val) return true;
    LD ans = LDBL_MAX;
    for(int i = 0 ; i < towers.size()-1 ; i++)
    {
        if(towers[i].first > l) break;
        LD point = towers[i].first;
        LD point2 = towers[i+1].first;
        if(val - towers[i].second * towers[i].second > 0)
            point = towers[i].first + sqrt(val - towers[i].second * towers[i].second);
        if(val - towers[i+1].second * towers[i+1].second > 0)
            point2 = towers[i+1].first - sqrt(val - towers[i+1].second * towers[i+1].second);
        if(point < point2)
            return true;
    }
    return false;
}
 
int solve(int testcase)
{
    cin >> n >> l;
    for(int i = 0; i < n; i++)
    {
        LD x, y;
        cin >> x >> y;
        if(!towers.size() || towers.back().first != x)
            towers.push_back({x, y});
    }
    LD low = 0, high = INT_MAX;
    LD mid, ans = INT_MAX;
    while(abs(high-low) > 1e-6)
    {
        mid = low + (high-low)/2;
        if(check(mid))
        {
            ans = mid;
            low = mid;
        }
        else high = mid;
    }
    cout << fixed << setprecision(7) << sqrt(ans) << endl;
    return 0;
}
 
signed main()
{
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    //cout.tie(NULL);
 
    solve(0);
    // TESTS
    return 0;
}
/*
2 10
0 0
11 -1
*/

Compilation message (stderr)

mobile.cpp: In function 'bool check(LD)':
mobile.cpp:49:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long double, long double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |     for(int i = 0 ; i < towers.size() ; i++)
      |                     ~~^~~~~~~~~~~~~~~
mobile.cpp:56:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long double, long double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |     for(int i = 0 ; i < towers.size()-1 ; i++)
      |                     ~~^~~~~~~~~~~~~~~~~
mobile.cpp:55:8: warning: unused variable 'ans' [-Wunused-variable]
   55 |     LD ans = LDBL_MAX;
      |        ^~~

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