Submission #606824

#	Time	Username	Problem	Language	Result	Execution time	Memory
606824		Hanksburger	Railway (BOI17_railway)	C++17	100 / 100	219 ms	34212 KiB

railway

#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > adj[100005];
map<int, int> mp[100005];
int s[100005], n, m, k;
vector<int> ans;
void dfs(int u, int p, int ind)
{
    for (int i=0; i<adj[u].size(); i++)
    {
        int v=adj[u][i].first, w=adj[u][i].second;
        if (v!=p)
        {
            dfs(v, u, w);
            if (mp[u].size()<mp[v].size())
                mp[u].swap(mp[v]);
            for (auto itr=mp[v].begin(); itr!=mp[v].end(); itr++)
            {
                mp[u][itr->first]+=itr->second;
                if (mp[u][itr->first]==s[itr->first])
                    mp[u].erase(itr->first);
            }
        }
    }
    if (mp[u].size()>=k)
        ans.push_back(ind);
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m >> k;
    for (int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    for (int i=1; i<=m; i++)
    {
        cin >> s[i];
        for (int j=1; j<=s[i]; j++)
        {
            int u;
            cin >> u;
            mp[u][i]++;
        }
    }
    dfs(1, 1, 0);
    cout << ans.size() << '\n';
    sort(ans.begin(), ans.end());
    for (int i:ans)
        cout << i << ' ';
    return 0;
}

Compilation message (stderr)

railway.cpp: In function 'void dfs(int, int, int)':
railway.cpp:9:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |     for (int i=0; i<adj[u].size(); i++)
      |                   ~^~~~~~~~~~~~~~
railway.cpp:25:21: warning: comparison of integer expressions of different signedness: 'std::map<int, int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   25 |     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