Submission #495510

#	Time	Username	Problem	Language	Result	Execution time	Memory
495510		hoanghq2004	Railway (BOI17_railway)	C++14	100 / 100	181 ms	39368 KiB

railway

#include <bits/stdc++.h>

using namespace std;

const int Nmax = 1e5 + 10;

int n, m, k;
unordered_map <int, int> mp[Nmax];
vector <pair <int, int> > e[Nmax];
int s[Nmax];
vector <int> ans;

void dfs(int u, int p, int ide) {
    for (auto [v, id]: e[u]) {
        if (v == p) continue;
        dfs(v, u, id);
        if (mp[u].size() < mp[v].size()) mp[u].swap(mp[v]);
        for (auto [i, x]: mp[v]) {
            mp[u][i] += x;
            if (mp[u][i] == s[i]) mp[u].erase(i);
        }
    }
    if (mp[u].size() >= k) ans.push_back(ide);
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n >> m >> k;
    for (int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        e[u].push_back({v, i});
        e[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, 0, 0);
    cout << ans.size() << '\n';
    sort(ans.begin(), ans.end());
    for (auto id: ans) cout << id << ' ';
}

Compilation message (stderr)

railway.cpp: In function 'void dfs(int, int, int)':
railway.cpp:14:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   14 |     for (auto [v, id]: e[u]) {
      |               ^
railway.cpp:18:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   18 |         for (auto [i, x]: mp[v]) {
      |                   ^
railway.cpp:23:22: warning: comparison of integer expressions of different signedness: 'std::unordered_map<int, int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   23 |     if (mp[u].size() >= k) ans.push_back(ide);
      |         ~~~~~~~~~~~~~^~~~

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