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Submission #393155

# Submission time Handle Problem Language Result Execution time Memory
393155 2021-04-22T20:20:18 Z dolphingarlic Potemkin cycle (CEOI15_indcyc) C++14
90 / 100
 717 ms 92544 KB 
/*
CEOI 2016 Potemkin Cycle
- Let each edge (u, v) represent a node (uv) in graph H
- There is an edge between (uv) and (vw) in H iff (uw) doesn't exist
    - This means that there are no cycles of length 3 in H
    - We can construct H in O(NR) time
- An answer exists iff a cycle exists in H; run DFS to find a cycle
*/

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

int u[200001], v[200001], adj[1001][1001];
vector<int> graph[200001], stck;
bool visited[200001], active[200001];

void dfs(int node, int parent = -1) {
    if (active[node]) {
        while (stck.back() != node) {
            cout << v[stck.back()] << ' ';
            stck.pop_back();
        }
        cout << v[node];
        exit(0);
    }
    if (visited[node]) return;

    stck.push_back(node);
    visited[node] = active[node] = true;
    for (int i : graph[node]) if (i != parent) dfs(i, node);
    stck.pop_back();
    active[node] = false;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n, r;
    cin >> n >> r;
    for (int i = 1; i <= r; i++) {
        cin >> u[i] >> v[i];
        u[i + r] = v[i], v[i + r] = u[i];
        adj[u[i]][v[i]] = i, adj[v[i]][u[i]] = i + r;
    }

    for (int i = 1; i <= 2 * r; i++) {
        for (int j = 1; j <= n; j++) if (j != u[i]) {
            if (adj[v[i]][j] && !adj[u[i]][j])
                graph[i].push_back(adj[v[i]][j]);
        }
    }

    for (int i = 1; i <= 2 * r; i++) if (!visited[i]) dfs(i);
    cout << "no";
    return 0;
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 4940 KB Output is correct
3 Correct 3 ms 4940 KB Output is correct
4 Correct 3 ms 4940 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5072 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5068 KB Output is correct
2 Correct 5 ms 5068 KB Output is correct

Subtask #4
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 4 ms 5452 KB Wrong adjacency

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 5580 KB Output is correct
2 Correct 6 ms 5708 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 6476 KB Output is correct
2 Correct 13 ms 6416 KB Output is correct
3 Correct 24 ms 8400 KB Output is correct
4 Correct 27 ms 8404 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 7736 KB Output is correct
2 Correct 15 ms 7800 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 354 ms 24748 KB Output is correct
2 Correct 115 ms 12156 KB Output is correct
3 Correct 369 ms 24644 KB Output is correct
4 Correct 118 ms 12216 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 210 ms 53572 KB Output is correct
2 Correct 244 ms 57760 KB Output is correct

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 206 ms 8736 KB Output is correct
2 Correct 207 ms 8640 KB Output is correct
3 Correct 625 ms 92364 KB Output is correct
4 Correct 717 ms 92544 KB Output is correct