Submission #570033

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
570033	2022-05-28T12:57:50 Z	600Mihnea	Potemkin cycle (CEOI15_indcyc)	C++17	100 / 100	587 ms	2824 KB

indcyc

#include <bits/stdc++.h>

using namespace std;

const int N = 1000 + 7;
const int INF = (int) 1e9 + 7;
int n, m, dist[N], par[N];
bool is_edge[N][N];
bool valid[N], vis[N];
vector<int> g[N], g2[N], gather;
int last_time[N], current_time;

void dfs(int a) {
  gather.push_back(a);
  vis[a] = 1;
  for (auto &b : g2[a]) {
    if (!vis[b] && valid[b]) {
      dfs(b);
    }
  }
}


signed main() {
  ios::sync_with_stdio(0); cin.tie(0);

  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int a, b;
    cin >> a >> b;
    g[a].push_back(b);
    g[b].push_back(a);
    is_edge[a][b] = is_edge[b][a] = 1;
  }
  for (int i = 1; i <= n; i++) {
    sort(g[i].begin(), g[i].end());
  }
  for (int root = 1; root <= n; root++) {
    for (int i = 1; i <= n; i++) {
      valid[i] = 1;
      vis[i] = 0;
      g2[i].clear();
    }
    valid[root] = 0;
    for (auto &v : g[root]) {
      valid[v] = 0;
    }
    for (int i = 1; i <= n; i++) {
      if (valid[i]) {
        for (auto &j : g[i]) {
          if (valid[j]) {
            g2[i].push_back(j);
          }
        }
      }
    }
    int v1_sol, v2_sol;
    bool found = 0;
    for (int zd = 1; zd <= n; zd++) {
      if (vis[zd] == 0 && valid[zd]) {
        gather.clear();
        dfs(zd);
        vector<int> verts;
        current_time++;
        for (auto &member : gather) {
          for (auto &copil : g[member]) {
            if (copil != root && !valid[copil] && last_time[copil] < current_time) {
              last_time[copil] = current_time;
              verts.push_back(copil);
            }
          }
        }
        if ((int) verts.size() >= 2) {
          for (auto &v1 : verts) {
            for (auto &v2 : verts) {
              if (found) break;
              if (v1 == v2) break;
              if (is_edge[v1][v2]) continue;

              v1_sol = v1;
              v2_sol = v2;
              found = 1;
            }
          }
        }
      }
    }
    if (!found) continue;
    int v1 = v1_sol, v2 = v2_sol;

    for (int i = 1; i <= n; i++) {
      dist[i] = INF;
      par[i] = 0;
    }
    dist[root] = -1;
    for (auto &v : g[root]) {
      if (v != v1 && v != v2) {
        dist[v] = -1;
      }
    }
    queue<int> q;
    dist[v1] = 0;
    q.push(v1);
    while (!q.empty()) {
      int a = q.front();
      q.pop();
      for (auto &b : g[a]) {
        if (dist[b] == INF) {
          dist[b] = 1 + dist[a];
          par[b] = a;
          q.push(b);
        }
      }
    }
    while (v2 != v1) {
      cout << v2 << " ";
      v2 = par[v2];
    }
    cout << v1 << " " << root << "\n";
    return 0;
  }
  cout << "no\n";
}

Compilation message

indcyc.cpp: In function 'int main()':
indcyc.cpp:115:15: warning: 'v1_sol' may be used uninitialized in this function [-Wmaybe-uninitialized]
  115 |     while (v2 != v1) {
      |            ~~~^~~~~

Subtask #1
10.0 / 10.0

#	Verdict	Memory	Grader output
1	Correct	340 KB	Output is correct
2	Correct	340 KB	Output is correct
3	Correct	340 KB	Output is correct
4	Correct	340 KB	Output is correct
5	Correct	340 KB	Output is correct

Subtask #2
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	340 KB	Output is correct

Subtask #3
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	340 KB	Output is correct
2	Correct	0 ms	340 KB	Output is correct

Subtask #4
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	468 KB	Output is correct

Subtask #5
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	468 KB	Output is correct
2	Correct	3 ms	508 KB	Output is correct

Subtask #6
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	15 ms	780 KB	Output is correct
2	Correct	1 ms	724 KB	Output is correct
3	Correct	3 ms	724 KB	Output is correct
4	Correct	20 ms	824 KB	Output is correct

Subtask #7
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	2 ms	724 KB	Output is correct
2	Correct	19 ms	764 KB	Output is correct

Subtask #8
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	17 ms	2420 KB	Output is correct
2	Correct	9 ms	1876 KB	Output is correct
3	Correct	533 ms	2432 KB	Output is correct
4	Correct	250 ms	1876 KB	Output is correct

Subtask #9
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	10 ms	1876 KB	Output is correct
2	Correct	342 ms	2016 KB	Output is correct

Subtask #10
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	23 ms	1788 KB	Output is correct
2	Correct	22 ms	1824 KB	Output is correct
3	Correct	30 ms	2764 KB	Output is correct
4	Correct	587 ms	2824 KB	Output is correct