Submission #570021

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
570021	2022-05-28T12:40:33 Z	600Mihnea	Potemkin cycle (CEOI15_indcyc)	C++17	70 / 100	1000 ms	1364 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], t[N];
bool valid[N];
vector<int> g[N];

void clr() {
  for (int i = 1; i <= n; i++) {
    t[i] = i;
  }
}

int get_root(int a) {
  if (t[a] == a) {
    return a;
  } else {
    return t[a] = get_root(t[a]);
  }
}

void join(int a, int b) {
  t[get_root(a)] = get_root(b);
}

bool is_edge(int a, int b) {
  int low = 0, high = (int) g[a].size() - 1;
  while (low <= high) {
    int mid = (low + high) / 2;
    if (g[a][mid] == b) {
      return 1;
    }
    if (g[a][mid] < b) {
      low = mid + 1;
    } else {
      high = mid - 1;
    }
  }
  return 0;
}

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

  ///freopen ("input.txt", "r", stdin);

  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);
  }
  for (int i = 1; i <= n; i++) {
    sort(g[i].begin(), g[i].end());
  }
  for (int root = 1; root <= n; root++) {
    clr();
    for (int i = 1; i <= n; i++) {
      valid[i] = 1;
    }
    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]) {
            join(i, j);
            if (i < j) {
           //   cout << " : " << i << " and " << j << "\n";
            }
          }
        }
      }
    }
    int v1_sol, v2_sol;
    bool found = 0;
    for (auto &v1 : g[root]) {

      for (auto &v2 : g[root]) {
        if (found) break;
        if (v1 == v2) break;
        if (is_edge(v1, v2)) continue;
        assert(valid[v1] == 0 && valid[v2] == 0);
        set<int> s1, s2;
        for (auto &i : g[v1]) {
          if (valid[i]) s1.insert(get_root(i));
        }
        for (auto &i : g[v2]) {
          if (valid[i]) s2.insert(get_root(i));
        }
        bool good = 0;

        for (auto &guy : s1) {
          if (s2.count(guy)) {
            good = 1;
          }
        }

        if (good) {
          found = 1;
          v1_sol = v1;
          v2_sol = v2;
        }
      }
    }
    if (!found) continue;
    int v1 = v1_sol, v2 = v2_sol;
 ///   cout << root << " : " << v1 << " " << v2 << "\n";

    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);
        }
      }
    }
    assert(dist[v1] != -1);
    if (dist[v2] != -1 && dist[v2] != INF) {
      while (v2 != v1) {
        cout << v2 << " ";
        v2 = par[v2];
      }
      cout << v1 << " " << root << "\n";
      exit(0);
    } else {
      assert(0);
    }

  }
  cout << "no\n";
  exit(0);
}

Compilation message

indcyc.cpp: In function 'int main()':
indcyc.cpp:146:21: warning: 'v2_sol' may be used uninitialized in this function [-Wmaybe-uninitialized]
  146 |       cout << v1 << " " << root << "\n";
      |                     ^~~

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	1 ms	340 KB	Output is correct

Subtask #4
10.0 / 10.0

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

Subtask #5
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	340 KB	Output is correct
2	Correct	6 ms	340 KB	Output is correct

Subtask #6
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	23 ms	408 KB	Output is correct
2	Correct	1 ms	340 KB	Output is correct
3	Correct	3 ms	340 KB	Output is correct
4	Correct	52 ms	416 KB	Output is correct

Subtask #7
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	340 KB	Output is correct
2	Correct	58 ms	340 KB	Output is correct

Subtask #8
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	22 ms	908 KB	Output is correct
2	Correct	9 ms	668 KB	Output is correct
3	Execution timed out	1087 ms	836 KB	Time limit exceeded
4	Halted	0 ms	0 KB	-

Subtask #9
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	15 ms	596 KB	Output is correct
2	Execution timed out	1096 ms	596 KB	Time limit exceeded
3	Halted	0 ms	0 KB	-

Subtask #10
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	70 ms	1364 KB	Output is correct
2	Correct	669 ms	1336 KB	Output is correct
3	Correct	66 ms	1084 KB	Output is correct
4	Execution timed out	1083 ms	980 KB	Time limit exceeded
5	Halted	0 ms	0 KB	-