Submission #1092791

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092791		juicy	Railway (BOI17_railway)	C++17	100 / 100	117 ms	39124 KiB

railway

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

const int N = 1e5 + 5;

int n, m, k;
int s[N];
map<int, int> mp[N];
vector<int> res;
vector<array<int, 2>> g[N];

void dfs(int u, int id) {
  for (auto [v, nxt] : g[u]) {
    if (nxt ^ id) {
      dfs(v, nxt);
      if (mp[u].size() < mp[v].size()) {
        mp[u].swap(mp[v]);
      }
      for (auto [c, x] : mp[v]) {
        mp[u][c] += x;
        if (mp[u][c] == s[c]) {
          mp[u].erase(c);
        }
      }
      map<int, int>().swap(mp[v]);
    }
  } 
  if (mp[u].size() >= k) {
    res.push_back(id);
  }
}

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  cin >> n >> m >> k;
  for (int i = 1; i < n; ++i) {
    int u, v; cin >> u >> v;
    g[u].push_back({v, i});
    g[v].push_back({u, i});
  }
  for (int i = 1; i <= m; ++i) {
    cin >> s[i];
    for (int j = 0; j < s[i]; ++j) {
      int u; cin >> u;
      ++mp[u][i];
    }
  }
  dfs(1, 0);
  sort(res.begin(), res.end());
  cout << res.size() << "\n";
  for (int x : res) {
    cout << x << " ";
  }
  return 0;
}

Compilation message (stderr)

railway.cpp: In function 'void dfs(int, int)':
railway.cpp:35:20: warning: comparison of integer expressions of different signedness: 'std::map<int, int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   35 |   if (mp[u].size() >= k) {
      |       ~~~~~~~~~~~~~^~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25