oj.uz

Submission #872847

# Submission time Handle Problem Language Result Execution time Memory
872847 2023-11-14T00:04:36 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
100 / 100
 176 ms 28384 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";
 
    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);
            }
        }
    };
 
    int col = 0;
    for(int i = 1; i <= n; i++) {
        if(compo[i] == -1) {
            dfsC(i, 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);
            nadj[max(x, y)].emplace_back(min(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, -1);
    function <void(int, int)> DFS = [&](int node, int par) -> void {
        //cerr << node << " ";
        vis[node] = 0;
        for(auto [child, num] : nadj[node]) {
            if(par == child)
                continue;
            if(vis[child] == -1)
                DFS(child, node);
            val[node] += val[child];
            vis[node] = max(vis[node], vis[child] +1);
        }
    };
 
    for(int i = 0; i < col; i++) {
        if(vis[i] == -1) {
            DFS(i, -1);
        }
    }
 
    //cerr << "\n";

    for(int i = 0; i < m; i++) {
        if(res[i] == 'X') {
            int x = compo[edges[i].first], y = compo[edges[i].second];
            //cerr << i << " || " << edges[i].first << " " << edges[i].second << " :: " << x << " " << y << " -> " << val[x] << " " << val[y] << " // " << vis[x] << " " << vis[y] << "\n";
            if(vis[x] > vis[y]) {
                if(val[y] > 0)
                    res[i] = 'L';
                else if(val[y] < 0)
                    res[i] = 'R';
                else
                    res[i] = 'B';
            } else if(vis[x] < vis[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 1 ms 344 KB Output is correct
2 Correct 0 ms 348 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 604 KB Output is correct
6 Correct 1 ms 348 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 1 ms 344 KB Output is correct
2 Correct 0 ms 348 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 604 KB Output is correct
6 Correct 1 ms 348 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 13112 KB Output is correct
12 Correct 92 ms 14460 KB Output is correct
13 Correct 101 ms 16352 KB Output is correct
14 Correct 106 ms 18256 KB Output is correct
15 Correct 134 ms 18880 KB Output is correct
16 Correct 160 ms 22176 KB Output is correct
17 Correct 108 ms 24120 KB Output is correct
18 Correct 119 ms 22100 KB Output is correct
19 Correct 114 ms 25692 KB Output is correct
20 Correct 94 ms 14348 KB Output is correct
21 Correct 74 ms 13624 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 0 ms 348 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 604 KB Output is correct
6 Correct 1 ms 348 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 13112 KB Output is correct
12 Correct 92 ms 14460 KB Output is correct
13 Correct 101 ms 16352 KB Output is correct
14 Correct 106 ms 18256 KB Output is correct
15 Correct 134 ms 18880 KB Output is correct
16 Correct 160 ms 22176 KB Output is correct
17 Correct 108 ms 24120 KB Output is correct
18 Correct 119 ms 22100 KB Output is correct
19 Correct 114 ms 25692 KB Output is correct
20 Correct 94 ms 14348 KB Output is correct
21 Correct 74 ms 13624 KB Output is correct
22 Correct 118 ms 24232 KB Output is correct
23 Correct 176 ms 21820 KB Output is correct
24 Correct 130 ms 22028 KB Output is correct
25 Correct 123 ms 28384 KB Output is correct
26 Correct 130 ms 23616 KB Output is correct
27 Correct 145 ms 22152 KB Output is correct
28 Correct 39 ms 4176 KB Output is correct
29 Correct 118 ms 13816 KB Output is correct
30 Correct 93 ms 13816 KB Output is correct
31 Correct 95 ms 14416 KB Output is correct
32 Correct 95 ms 16724 KB Output is correct