Submission #1036547

#	Time	Username	Problem	Language	Result	Execution time	Memory
1036547		model_code	Sprinklers (CEOI24_sprinklers)	C++17	20 / 100	2068 ms	1288 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) {
    int i = 0;
    vector<int> cover(f.size(), 0);

    for (; i < s.size(); i++) {
        int l, r;
        if (c[i] == 0) {
            l = s[i] - K;
            r = s[i];
        }
        else {
            l = s[i];
            r = s[i] + K;
        }
        for (int j = 0; j < f.size(); j++) {
            if (l <= f[j] && f[j] <= r) {
                cover[j]++;
            }
        }
    }

    bool covered = true;
    for (auto&& x : cover) {
        covered = x > 0;
        if (!covered) break;
    }
    return covered;
}

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