Submission #309963

#	Time	Username	Problem	Language	Result	Execution time	Memory
309963		VROOM_VARUN	Pipes (CEOI15_pipes)	C++14	0 / 100	1707 ms	65536 KiB

pipes

/*
ID: varunra2
LANG: C++
TASK: pipes
*/

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

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

int n, m;                 // number of nodes
vector<vector<int>> adj;  // adjacency list of graph

vector<bool> visited;
vector<int> tin, low;
int timer;

VII ret;

void IS_BRIDGE(int u, int v) {
  // debug("here");
  ret.PB(MP(u, v));
}

void dfs(int v, int p = -1) {
  visited[v] = true;
  tin[v] = low[v] = timer++;
  for (int to : adj[v]) {
    if (to == p) continue;
    if (visited[to]) {
      low[v] = min(low[v], tin[to]);
    } else {
      dfs(to, v);
      low[v] = min(low[v], low[to]);
      if (low[to] > tin[v]) IS_BRIDGE(v, to);
    }
  }
}

void find_bridges() {
  timer = 0;
  visited.assign(n, false);
  tin.assign(n, -1);
  low.assign(n, -1);
  for (int i = 0; i < n; ++i) {
    if (!visited[i]) dfs(i);
  }
}

void init() { adj.resize(n); }

struct dsu {
  VI par;
  VI siz;
  void init(int n) {
    par.resize(n);
    siz.resize(n);
    rep(i, 0, n) par[i] = i, siz[i] = 1;
  }

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

  bool merge(int x, int y) {
    // debug("here");
    x = find(x);
    y = find(y);
    if (x == y) return false;
    if (siz[y] > siz[x]) swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;
  }
};

int main() {
// #ifndef ONLINE_JUDGE
  // freopen("pipes.in", "r", stdin);
  // freopen("pipes.out", "w", stdout);
// #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> n >> m;

  dsu dsu1;
  dsu dsu2;

  init();

  dsu1.init(n);
  dsu2.init(n);

  int u, v;

  for (int i = 0; i < m; i++) {
    cin >> u >> v;
    u--, v--;
    if (dsu1.merge(u, v)) {
      // debug("here");
      adj[u].PB(v);
      adj[v].PB(u);
    } else {
      if (dsu2.merge(u, v)) {
        // debug("here");
        adj[u].PB(v);
        adj[v].PB(u);
      }
    }
  }

  // debug(adj);

  find_bridges();

  sort(all(ret));
  trav(x, ret) { cout << x.x + 1 << " " << x.y + 1 << '\n'; }

  return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10