Submission #585279

#	Time	Username	Problem	Language	Result	Execution time	Memory
585279		Jomnoi	One-Way Streets (CEOI17_oneway)	C++17	0 / 100	2 ms	2644 KiB

oneway

#include <bits/stdc++.h>
using namespace std;

const int MAX_N = 1e5 + 5;
const int MAX_M = 1e5 + 5;

vector <int> graph[MAX_N];
int L[MAX_M], R[MAX_M];
int X[MAX_N], Y[MAX_N];
bool visited[MAX_N];
bool is_cycle[MAX_M];
int qs[MAX_N];

void dfs(int u, int p) {
    visited[u] = true;
    for(auto i : graph[u]) {
        int v = u ^ L[i] ^ R[i];
        if(v == p) {
            continue;
        }

        if(visited[v] == false) {
            dfs(v, u);
        }
        else {
            is_cycle[i] = true;
            // qs[u]++;
            // qs[v]--;
        }
    }
}

void dfs2(int u) {
    visited[u] = true;
    for(auto i : graph[u]) {
        int v = u ^ L[i] ^ R[i];
        if(visited[v] == false) {
            dfs2(v);
            qs[u] += qs[v];
        }
    }
}

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    for(int i = 1; i <= m; i++) {
        cin >> L[i] >> R[i];

        graph[L[i]].push_back(i);
        graph[R[i]].push_back(i);
    }

    for(int i = 1; i <= n; i++) {
        if(visited[i] == false) {
            dfs(i, -1);
        }
    }

    int p;
    cin >> p;
    
    for(int i = 1; i <= p; i++) {
        cin >> X[i] >> Y[i];

        qs[X[i]]++;
        qs[Y[i]]--;
    }

    fill(visited + 1, visited + n + 1, false);
    for(int i = 1; i <= n; i++) {
        if(visited[i] == false) {
            dfs2(i);
        }
    }

    for(int i = 1; i <= m; i++) {
        if(is_cycle[i] == true) {
            cout << 'B';
            continue;
        }

        if(qs[L[i]] < 0 or qs[R[i]] > 0) {
            cout << 'L';
        }
        else if(qs[L[i]] > 0 or qs[R[i]] < 0) {
            cout << 'R';
        }
        else {
            cout << 'B';
        }
    }
    return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40