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Submission #872657

# Submission time Handle Problem Language Result Execution time Memory
872657 2023-11-13T13:50:33 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
100 / 100
 143 ms 27428 KB 
//author: Ahmet Alp Orakci
#include <bits/stdc++.h>
using namespace std;
using i64 = long long;

#define ONLINE_JUDGE
void solve() {
    int n, m;
    cin >> n >> m;

    map <pair <int, int>, int> mp;
    vector <pair <int, int>> adj[n +1];
    vector <pair <int, int>> edges(m);
    for(int i = 0; i < m; i++) {
        cin >> edges[i].first >> edges[i].second;
        adj[edges[i].first].emplace_back(edges[i].second, i);
        adj[edges[i].second].emplace_back(edges[i].first, i);
        mp[{min(edges[i].first, edges[i].second), max(edges[i].first, edges[i].second)}]++;
    }

    int timer = 0;
    vector <int> tin(n +1, -1), low(n +1, -1), is_bridge(m);
    function <void(int, int)> dfs = [&](int node, int par) -> void {
        low[node] = tin[node] = timer++;
        for(auto [child, number] : adj[node]) {
            if(child == par) {
                continue;
            }

            if(tin[child] == -1) {
                dfs(child, node);
                low[node] = min(low[node], low[child]);
                if(low[child] > tin[node]) {
                    //cerr << node << " " << child << " :: " << number << "\n";
                    is_bridge[number] = true;
                }
            } else {
                low[node] = min(low[node], tin[child]);
            }
        }
    };

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

    string res(m, 'B');
    for(int i = 0; i < m; i++) {
        if(mp[{min(edges[i].first, edges[i].second), max(edges[i].first, edges[i].second)}] > 1) {
            //cerr << edges[i].first << " " << edges[i].second << " :: " << i << "\n";
            is_bridge[i] = false;
        }

        if(is_bridge[i]) {
            res[i] = 'X';
        }
    }

    //cerr << res << "\n";

    queue <int> q;
    vector <int> compo(n +1, -1);
    function <void(int, int)> dfsC = [&](int node, int color) {
        compo[node] = color;
        for(auto [child, num] : adj[node]) {
            if(compo[child] == -1 && !is_bridge[num]) {
                dfsC(child, color);
            } else if(compo[child] == -1) {
                q.emplace(child);
            }
        }
    };

    int col = 0;
    for(int i = 1; i <= n; i++) {
        if(compo[i] == -1) {
            dfsC(i, col);
            col++;
        }

        while(!q.empty()) {
            int x = q.front();
            q.pop();
            if(compo[x] != -1)
                continue;
            
            dfsC(x, col);
            col++;
        }
    }

    /*
    for(int i = 1; i <= n; i++) {
        cerr << compo[i] << " \n"[i == n];
    }
    */

    vector <pair <int, int>> nadj[col];
    for(int i = 0; i < m; i++) {
        if(is_bridge[i]) {
            int x = compo[edges[i].first], y = compo[edges[i].second];
            //cerr << i << " -> " << edges[i].first << " " << edges[i].second << " :: " << compo[edges[i].first] << " " << compo[edges[i].second] << "\n";
            nadj[min(x, y)].emplace_back(max(x, y), i);
        }
    }

    int p;
    cin >> p;

    vector <int> val(col);
    for(int i = 1; i <= p; i++) {
        int a, b;
        cin >> a >> b;
        //cerr << a << " " << b << " :: " << compo[a] << " " << compo[b] << "\n";
        val[compo[a]]++;
        val[compo[b]]--;
    }

    vector <int> vis(col);
    function <void(int)> DFS = [&](int node) -> void {
        vis[node] = true;
        for(auto [child, num] : nadj[node]) {
            if(!vis[child])
                DFS(child);
            val[node] += val[child];
        }
    };

    for(int i = 0; i < col; i++) {
        if(!vis[i]) {
            DFS(i);
        }
    }

    for(int i = 0; i < m; i++) {
        if(res[i] == 'X') {
            int x = compo[edges[i].first], y = compo[edges[i].second];
            //cerr << edges[i].first << " " << edges[i].second << " :: " << x << " " << y << " -> " << val[x] << " " << val[y] << "\n";
            if(x < y) {
                if(val[y] > 0)
                    res[i] = 'L';
                else if(val[y] < 0)
                    res[i] = 'R';
                else
                    res[i] = 'B';
            } else if(x > y) {
                if(val[x] > 0)
                    res[i] = 'R';
                else if(val[x] < 0)
                    res[i] = 'L';
                else
                    res[i] = 'B';
            } else {
                res[i] = 'B';
            }
        }
    }

    cout << res;
    
    return;
}

signed main() {
    #ifndef ONLINE_JUDGE
        freopen(".in", "r", stdin);
        freopen(".out", "w", stdout);
    #endif

    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    int t = 1; //cin >> t;
    for(int i = 1; i <= t; i++) {
        solve();
    }

    return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 452 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 600 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 452 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 600 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 89 ms 14416 KB Output is correct
12 Correct 89 ms 16088 KB Output is correct
13 Correct 111 ms 18000 KB Output is correct
14 Correct 142 ms 19688 KB Output is correct
15 Correct 117 ms 20036 KB Output is correct
16 Correct 129 ms 21264 KB Output is correct
17 Correct 123 ms 23452 KB Output is correct
18 Correct 122 ms 21384 KB Output is correct
19 Correct 116 ms 24484 KB Output is correct
20 Correct 94 ms 15444 KB Output is correct
21 Correct 86 ms 14820 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 1 ms 452 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 600 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 89 ms 14416 KB Output is correct
12 Correct 89 ms 16088 KB Output is correct
13 Correct 111 ms 18000 KB Output is correct
14 Correct 142 ms 19688 KB Output is correct
15 Correct 117 ms 20036 KB Output is correct
16 Correct 129 ms 21264 KB Output is correct
17 Correct 123 ms 23452 KB Output is correct
18 Correct 122 ms 21384 KB Output is correct
19 Correct 116 ms 24484 KB Output is correct
20 Correct 94 ms 15444 KB Output is correct
21 Correct 86 ms 14820 KB Output is correct
22 Correct 122 ms 24404 KB Output is correct
23 Correct 125 ms 22864 KB Output is correct
24 Correct 143 ms 22448 KB Output is correct
25 Correct 129 ms 27428 KB Output is correct
26 Correct 119 ms 23892 KB Output is correct
27 Correct 122 ms 22868 KB Output is correct
28 Correct 40 ms 5212 KB Output is correct
29 Correct 116 ms 16360 KB Output is correct
30 Correct 95 ms 16212 KB Output is correct
31 Correct 102 ms 17004 KB Output is correct
32 Correct 87 ms 19180 KB Output is correct