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Submission #711693

# Submission time Handle Problem Language Result Execution time Memory
711693 2023-03-17T11:15:23 Z Pety Pipes (CEOI15_pipes) C++14
90 / 100
 3781 ms 14488 KB 
#include <vector>
#include <iostream>
#include <cassert>

using namespace std;

int n, m, x, y, sz[100002], p[100002], dp[20][100002], depth[100002];
vector<int>G[100002];

int find (int x) {
  if (p[x] == x)
    return x;
  return p[x] = find(p[x]);
}

void dfs2 (int x, int par) {
  dp[0][x] = par;
  depth[x] = depth[par] + 1;
  for (int i = 1; (1 << i) < n; i++)
    dp[i][x] = dp[i - 1][dp[i - 1][x]];
  for (auto it : G[x]) {
    if (it == par)
      continue;
    dfs2(it, x);
  }
}
int cnt;
void merge (int x, int y) {
  int px = find(x);
  int py = find(y);
  if (px == py)
    return;

  if (sz[px] > sz[py]) {
    swap(x, y);
    swap(px, py);
  }
  G[x].push_back(y);
  G[y].push_back(x);

  p[px] = py;
  sz[py] += sz[px];
  dfs2(x, y);
}

int lca (int x, int y) {
  if (depth[x] > depth[y])
    swap(x, y);
  int d = depth[y] - depth[x];
  for (int i = 0; (1 << i) <= d; i++)
    if (d & (1 << i))
      y = dp[i][y];
  if (x == y)
    return x;
  for (int i = 19; i >= 0; i--)
    if ((1 << i) != n && dp[i][x] != dp[i][y]) {
      x = dp[i][x];
      y = dp[i][y];
    }
  return dp[0][x];
}

int add[100002], viz[100002];

void dfs (int x, int par) {
  viz[x] = 1;
  for (auto it : G[x]) {
    if (it == par)
      continue;
    dfs(it, x);
    add[x] += add[it];
  }
  if (add[x] == 0 && par != 0)
    cout << x << " " << par << "\n";
}

void dfs3 (int x, int par) {
  depth[x] = depth[par] + 1;
  viz[x] = 1;
  sz[x] = 1e9;
  for (auto it : G[x]) {
    if (!viz[it]) {
      dfs3(it, x);
      sz[x] = min(sz[it], sz[x]);
    }
    else if (depth[it] < depth[x]-1) {
      sz[x] = min(depth[it], sz[x]);
    }
  }
  if (sz[x] >= depth[x] && par != 0) {
    cout << x << " " << par << "\n";
  }
}

int main () 
{
  ios_base::sync_with_stdio(false);
  cin.tie(0); cout.tie(0);
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    p[i] = i;
    sz[i] = 1;
  }
  if (m <= 200) {
    for (int i = 1; i <= m; i++) {
      int x, y;
      cin >> x >> y;
      assert(x >= 1 && x <= n && y >= 1 && y <= n);
      G[x].push_back(y);
      G[y].push_back(x);
    }
    for (int i = 1; i <= n; i++)
      if (!viz[i])
        dfs3(i, 0);
    return 0;
  }
  for (int i = 1; i <= m; i++) {
    cin >> x >> y;
    if (find(x) == find(y)) {
      int L = lca(x, y);
      assert(L > 0);
      add[L] -= 2;
      add[x]++;
      add[y]++;
    }
    else {
      merge(x, y);
      //assert(abs(depth[x] - depth[y]) == 1);
    }
  }
  for (int i = 1; i <= n; i++)
    if (!viz[find(i)])
      dfs(find(i), 0);
  return 0;
}

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Incorrect 2 ms 2644 KB Wrong number of edges
3 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 3196 KB Output is correct
2 Correct 8 ms 3156 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 140 ms 3084 KB Output is correct
2 Correct 147 ms 3052 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 323 ms 3736 KB Output is correct
2 Correct 306 ms 3708 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 473 ms 5244 KB Output is correct
2 Correct 469 ms 5984 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 889 ms 10936 KB Output is correct
2 Correct 827 ms 11640 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1764 ms 12168 KB Output is correct
2 Correct 1594 ms 12076 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2526 ms 14364 KB Output is correct
2 Correct 2478 ms 14480 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2847 ms 14356 KB Output is correct
2 Correct 2659 ms 14488 KB Output is correct

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3781 ms 13660 KB Output is correct
2 Correct 3127 ms 14476 KB Output is correct