Submission #1052625

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052625		turska	Railway (BOI17_railway)	C++17	100 / 100	115 ms	31248 KiB

railway

#include <bits/stdc++.h>
using namespace std;
 
#define all(v) (v).begin(), (v).end()

 
int n, m, k;
vector<pair<int, int>> adj[100001];
vector<int> q[100001];
 
int z[100001];
 
vector<int> ans;
 
map<int, int> dfs(int v, int p) {
    map<int, int> a;
 
    for (auto [u, i]: adj[v]) if (u!=p) {
        map<int, int> b = dfs(u, v);
 
        if (b.size()>=k) {
            ans.push_back(i);
        }
 
        if (a.size() < b.size()) a.swap(b);
        for (auto [k, v]: b) {
            if (a[k]+v==z[k]) a.erase(k);
            else a[k] += v;
        }
    }
 
    for (auto u: q[v]) {
        a[u]++;
        if (a[u] == z[u]) a.erase(u);
    }
    return a;
}
 
int main() {
    cin >> n >> m >> k;
 
    for (int i=0; i<n-1; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    for (int i=0; i<m; i++) {
        int s;
        cin >> s;
        z[i] = s;
        for (int j=0; j<s; j++) {
            int k;
            cin >> k;
            q[k].push_back(i);
        }
    }
    dfs(1, 1);
    sort(all(ans));
    cout << ans.size() << '\n';
    for (auto i: ans) cout << i+1 << ' ';
}

Compilation message (stderr)

railway.cpp: In function 'std::map<int, int> dfs(int, int)':
railway.cpp:21:21: warning: comparison of integer expressions of different signedness: 'std::map<int, int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   21 |         if (b.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