Submission #1140529

#	Time	Username	Problem	Language	Result	Execution time	Memory
1140529		marinov	Sprinklers (CEOI24_sprinklers)	C++20	20 / 100	2092 ms	2856 KiB

Main

// Authors: Robert Jaworski
#include <bits/stdc++.h>

#pragma GCC diagnostic ignored "-Wsign-compare"
using namespace std;

bool check(int K, const std::vector<int>& s, const std::vector<int>& f, const vector<int>& c, bool verbose=false) {
	vector<pair<int, int>> events; // place, type {-1: begin of cover interval, 0: flower, 1: end of cover interval} (order of types is important for sorting)

	for(int it: f) events.push_back({it, 0});

	for(int i=0; i<s.size(); i++)
	{
		if(c[i]==0)
		{
			events.push_back({s[i]-K, -1});
			events.push_back({s[i], 1});
		}
		else
		{
			events.push_back({s[i], -1});
			events.push_back({s[i]+K, 1});
		}
	}

	sort(events.begin(), events.end());

	int open_intervals=0;
	for(auto [place, type]: events)
	{
		open_intervals -= type;
		if(type == 0 && !open_intervals)
		{
			return false;
		}
	}

	return true;
}

bool bruteforce(int N, int M, int K, const vector<int>& s, const vector<int>& f, std::vector<int>& conf) {
    conf.resize(N, 0);
    for (int i = 0; i != N;) {
        if (check(K, s, f, conf)) return true;

        for (i = 0; i < N; i++) {
            conf[i] ^= 1;
            if (conf[i]) break;
        }
    }

    return false;
}

int main() {
    int N, M;
    cin >> N >> M;

    vector<int> s(N, 0), f(M, 0), conf;
    for (auto&& x : s) {
        cin >> x;
    }
    for (auto&& x : f) {
        cin >> x;
    }

    if (N == 1) {
        if (s.back() <= f[0]) {
            cout << (f.back() - s.back()) << endl << "R" << endl;
        }
        else if (s[0] >= f.back()) {
            cout << (s[0] - f[0]) << endl << "L" << endl;
        }
        else {
            cout << -1 << endl;
        }
        return 0;
    }

    int maxK = 1;
    int K, l, r;
    if (bruteforce(N, M, 0, s, f, conf)) {
        K = 0;
        goto END;
    }

    while (!bruteforce(N, M, maxK, s, f, conf)) maxK <<= 1;

    l = maxK / 2;
    r = maxK;
    while (l+1 < r) {
        int m = (l+r) / 2;
        if (bruteforce(N, M, m, s, f, conf)) {
            r = m;
        }
        else {
            l = m;
        }
    }

    K = r;
    if (!bruteforce(N, M, K, s, f, conf)) {
        cout << "Very bad" << endl;
    }

END:
    cout << K << endl;
    for (auto&& x : conf) {
        cout << (x ? 'R' : 'L');
    }
    cout << endl;

    return 0;
}

• Subtask 0: 0 / 0
• Subtask 1: 3 / 3
• Subtask 2: 0 / 6
• Subtask 3: 17 / 17
• Subtask 4: 0 / 27
• Subtask 5: 0 / 47