Submission #577634

#	Time	Username	Problem	Language	Result	Execution time	Memory
577634		tengiz05	Roads (CEOI20_roads)	C++17	0 / 100	1 ms	468 KiB

roads

#include <bits/stdc++.h>

using namespace std;
using i64 = long long;

constexpr int inf = 1E9;

int Time;

struct Line {
    int x, y;
    double s;
    pair<int, int> l, r;
    Line(int x1, int y1, int x2, int y2) {
        x = x1;
        y = y1;
        if (x2 - x1 == 0) {
            s = 0;
        } else {
            s = 1. * (y2 - y1) / (x2 - x1);
        }
        l = r = {x1, y1};
    }
    double at() {
        return y + (Time - x) * s;
    }
};
double at(const Line x) {
    return x.y + (Time - x.x) * x.s;
}
inline bool operator<(const Line &a, const Line &b) {
    if (at(a) - at(b) < -1e-9)
        return true;
    return false;
}

bool bad(const pair<int, int> &x) {
    return abs(x.first) == inf;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n;
    cin >> n;
    
    vector<tuple<int, int, int>> events;
    
    vector<int> X1(n + 2), Y1(n + 2), X2(n + 2), Y2(n + 2);
    
    for (int i = 1; i <= n; i++) {
        int x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        X1[i] = x1;
        Y1[i] = y1;
        X2[i] = x2;
        Y2[i] = y2;
        if (x1 > x2) {
            swap(x1, x2);
            swap(y1, y2);
        } else if (x1 == x2 && y1 > y2) {
            swap(y1, y2);
        }
        events.emplace_back(x1, y1, i);
        events.emplace_back(x2, y2, -i);
        
    }
    
    sort(events.begin(), events.end());
    
    set<Line> s;
    s.insert(Line(-inf, -inf, inf, -inf));
    s.insert(Line(-inf, inf, inf, inf));
    
    for (auto [x, y, i] : events) {
        Time = x;
        // cerr << "Checking " << x << " " << y << ", " << i << "\n";
            // for (auto x : s) {
                // cout << at(x) << " : ";
                // cout << x.x << " " << x.y << "\n";
            // }
        if (i > 0) {
            auto L = *prev(s.upper_bound(Line(x, y, x, y)));
            auto R = *s.upper_bound(Line(x, y, x, y));
            assert(s.upper_bound(Line(x, y, x, y)) != s.end());
            cout << at(Line(x, y, x, y));
            // cout << "this is it  " << R.x << " " << R.y << "\n";
            if (!bad(L.r)) {
                // cout << "HMM\n";
                cout << x << " " << y << " " << L.r.first << " " << L.r.second << "\n";
            } else if (!bad(R.l)) {
                // cout << "SD\n";
                cout << x << " " << y << " " << R.l.first << " " << R.l.second << "\n";
            } else {
            }
            s.insert(Line(x, y, X2[i], Y2[i]));
        } else {
            auto L = *prev(s.lower_bound(Line(x, y, x, y)));
            auto R = *s.upper_bound(Line(x, y, x, y));
            L.r = {x, y};
            R.l = {x, y};
            s.erase(L);
            s.erase(R);
            s.insert(L);
            s.insert(R);
            auto c = *s.lower_bound(Line(X1[-i], Y1[-i], x, y));
            // cout << at(Line(X1[-i], Y1[-i], x, y)) << ",," << X1[-i] << " " << Y1[-i] << "\n";
            // cout << " we are about to end this man's whole career: " << c.x << " " << c.y << "\n";
            s.erase(s.lower_bound(Line(X1[-i], Y1[-i], x, y)));
        }
    }
    
    return 0;
}

Compilation message (stderr)

roads.cpp: In function 'int main()':
roads.cpp:107:18: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  107 |             auto c = *s.lower_bound(Line(X1[-i], Y1[-i], x, y));
      |                  ^

• Subtask 1: 0 / 0
• Subtask 2: 0 / 15
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 40