Submission #1059381

#	Time	Username	Problem	Language	Result	Execution time	Memory
1059381		MilosMilutinovic	Potemkin cycle (CEOI15_indcyc)	C++14	100 / 100	604 ms	2424 KiB

indcyc

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

const int N = 1005;

int p[N], sz[N];

int root(int x) {
  return p[x] == x ? x : p[x] = root(p[x]);
}

void Merge(int x, int y) {
  x = root(x);
  y = root(y);
  if (x == y) {
    return;
  }
  if (sz[x] < sz[y]) {
    swap(x, y);
  }
  sz[x] += sz[y];
  p[y] = x;
}
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m; 
  vector<vector<bool>> c(n, vector<bool>(n));
  vector<bitset<N>> cb(n);
  vector<vector<int>> g(n);
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    c[x][y] = true;
    c[y][x] = true;
    g[x].push_back(y);
    g[y].push_back(x);
    cb[x][y] = 1;
    cb[y][x] = 1;
  }
  auto Solve = [&](int i, int j, int k) {
    vector<bool> del(n);
    del[k] = true;
    for (int p : g[k]) {
      if (p != i && p != j) {
        del[p] = true;
      }
    }
    vector<int> p(n, -1);
    vector<int> que(1, i);
    vector<int> d(n, -1);
    d[i] = 0;
    for (int b = 0; b < (int) que.size(); b++) {
      int i = que[b];
      for (int j : g[i]) {
        if (del[j]) {
          continue;
        }
        if (d[j] == -1) {
          p[j] = i;
          d[j] = d[i] + 1;
          que.push_back(j);
        }
      }
    }
    vector<int> seq;
    for (int v = j; v != -1; v = p[v]) {
      seq.push_back(v);
    }
    seq.push_back(k);
    for (int i = 0; i < (int) seq.size(); i++) {
      cout << seq[i] + 1 << " ";
    }
    cout << '\n';
  };
  mt19937 rng(time(0));
  vector<int> order(n);
  iota(order.begin(), order.end(), 0);
  shuffle(order.begin(), order.end(), rng);
  for (int k : order) {
    vector<bool> del(n);
    del[k] = true;
    for (int i : g[k]) {
      del[i] = true;
    }
    for (int i = 0; i < n; i++) {
      p[i] = i;
      sz[i] = 1;
    }
    for (int i = 0; i < n; i++) {
      if (del[i]) {
        continue;
      }
      for (int j : g[i]) {
        if (del[j]) {
          continue;
        }
        Merge(i, j);
      }
    }
    vector<vector<int>> ids(n);
    for (int i = 0; i < n; i++) {
      if (!c[i][k]) {
        continue;
      }
      for (int j : g[i]) {
        if (del[j]) {
          continue;
        }
        ids[root(j)].push_back(i);
      }
    }
    for (int i = 0; i < n; i++) {
      sort(ids[i].begin(), ids[i].end());
      ids[i].erase(unique(ids[i].begin(), ids[i].end()), ids[i].end());
      sort(ids[i].begin(), ids[i].end(), [&](int i, int j) {
        return (int) g[i].size() > (int) g[j].size();
      });
      int sz = (int) ids[i].size();
      if ((int) ids[i].size() >= 300) {
        bitset<N> bs;
        bool found = false;
        for (int x = 0; x < sz; x++) {
          if ((cb[ids[i][x]] & bs) != bs) {
            found = true;
            break;
          }
          bs[ids[i][x]] = 1;
        }
        if (!found) {
          continue;
        }
      }
      for (int x = 0; x < sz; x++) {
        for (int y = x + 1; y < sz; y++) {
          if (!c[ids[i][x]][ids[i][y]]) {
            Solve(ids[i][x], ids[i][y], k);
            return 0;
          }
        }
      }
    }
  }
  cout << "no" << '\n';
  return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10