oj.uz

Submission #872842

# Submission time Handle Problem Language Result Execution time Memory
872842 2023-11-13T23:42:01 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
100 / 100
 130 ms 26632 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;
} // 23 orz

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 600 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 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 600 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 84 ms 14164 KB Output is correct
12 Correct 88 ms 15596 KB Output is correct
13 Correct 107 ms 17540 KB Output is correct
14 Correct 110 ms 19284 KB Output is correct
15 Correct 115 ms 19716 KB Output is correct
16 Correct 121 ms 20936 KB Output is correct
17 Correct 130 ms 23288 KB Output is correct
18 Correct 118 ms 21072 KB Output is correct
19 Correct 105 ms 23892 KB Output is correct
20 Correct 93 ms 15184 KB Output is correct
21 Correct 86 ms 14356 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 600 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 84 ms 14164 KB Output is correct
12 Correct 88 ms 15596 KB Output is correct
13 Correct 107 ms 17540 KB Output is correct
14 Correct 110 ms 19284 KB Output is correct
15 Correct 115 ms 19716 KB Output is correct
16 Correct 121 ms 20936 KB Output is correct
17 Correct 130 ms 23288 KB Output is correct
18 Correct 118 ms 21072 KB Output is correct
19 Correct 105 ms 23892 KB Output is correct
20 Correct 93 ms 15184 KB Output is correct
21 Correct 86 ms 14356 KB Output is correct
22 Correct 121 ms 23380 KB Output is correct
23 Correct 120 ms 21636 KB Output is correct
24 Correct 129 ms 21588 KB Output is correct
25 Correct 122 ms 26632 KB Output is correct
26 Correct 118 ms 22868 KB Output is correct
27 Correct 117 ms 21844 KB Output is correct
28 Correct 39 ms 4900 KB Output is correct
29 Correct 113 ms 14984 KB Output is correct
30 Correct 93 ms 15276 KB Output is correct
31 Correct 98 ms 15976 KB Output is correct
32 Correct 87 ms 18256 KB Output is correct