Submission #574682

#	Time	Username	Problem	Language	Result	Execution time	Memory
574682		piOOE	Roads (CEOI20_roads)	C++17	15 / 100	31 ms	4300 KiB

roads

#include <bits/stdc++.h>

using namespace std;

#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;
#define y1 pi300iq

typedef long long ll;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }

const int N = 200000, infI = 1e9 + 7;

int X[N], Y[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<pair<int, int>> yy;
    bool ok = true;
    for (int i = 0; i < n; ++i) {
        int x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        if (x1 > x2 || (x1 == x2 && y1 > y2)) {
            swap(x1, x2);
            swap(y1, y2);
        }
        X[i << 1] = x1, Y[i << 1] = y1;
        X[i << 1 | 1] = x2, Y[i << 1 | 1] = y2;
        yy.emplace_back(x1, y1);
        yy.emplace_back(x2, y2);
        ok &= X[i << 1] == X[i << 1 | 1];
    }
    sort(all(yy));
    auto get_idx = [&yy](int x, int y) {
        int it = lower_bound(all(yy), make_pair(x, y)) - begin(yy);
        if (it == sz(yy) || yy[it] != make_pair(x, y)) {
            return -1;
        }
        return it;
    };
    if (ok) {
        map<int, vector<pair<int, int>>> mp;
        for (int i = 0; i < n; ++i) {
            mp[X[i << 1]].emplace_back(Y[i << 1], Y[i << 1 | 1]);
        }
        pair<int, int> lst = {-infI, -infI};
        for (auto [x, a]: mp) {
            sort(all(a));
            if (lst.first != -infI) {
                cout << lst.first << " " << lst.second << " " << x << " " << a[0].first << '\n';
            }
            lst = {x, a[0].first};
            for (int i = 0; i < sz(a) - 1; ++i) {
                cout << x << " " << a[i].second << " " << x << " " << a[i + 1].first << '\n';
            }
        }
    } else {
        //I assume that every segment is parallel to each other
        pair<ll, ll> K = {(Y[0] - Y[1]), (X[0] - X[1])};
        auto comp = [](pair<ll, ll> a, pair<ll, ll> b) -> bool {
            if (b.second < 0) {
                b.first *= -1;
                b.second *= -1;
            }
            if (a.second < 0) {
                a.second *= -1;
                a.first *= -1;
            }
            return (a.first * b.second < a.second * b.first);
        };
        auto cmp = [&K, &comp](int i, int j) {
            if (X[i << 1] == X[j << 1]) {
                return Y[i << 1] < Y[j << 1];
            }
            return comp({Y[i << 1] - Y[j << 1], X[i << 1] - X[j << 1]}, K);
        };
        vector<int> ord(n);
        iota(all(ord), 0);
        sort(all(ord), cmp);
        pair<int, int> lst = {-infI, -infI};
        for (int i = 0; i < n; ++i) {
            int x = ord[i];
            if (lst.first != -infI)
                cout << lst.first << " " << lst.second << " " << X[x << 1] << " " << Y[x << 1] << '\n';
            lst = {X[x << 1 | 1], Y[x << 1 | 1]};
        }
    }
    return 0;
}

Compilation message (stderr)

roads.cpp: In function 'int main()':
roads.cpp:41:10: warning: variable 'get_idx' set but not used [-Wunused-but-set-variable]
   41 |     auto get_idx = [&yy](int x, int y) {
      |          ^~~~~~~

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