Submission #503884

#	Time	Username	Problem	Language	Result	Execution time	Memory
503884		ac2hu	Railway (BOI17_railway)	C++14	0 / 100	74 ms	29840 KiB

railway

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int LG = log2(N) + 10;
vector<int> adj[N];
int n,m,k,l, timer = 0;
vector<pair<int,int>> edges;
int lca_util[N][LG];
int tin[N],tout[N];
int dist[N];
int ans[N];
void dfs(int i,int p){
	tin[i] = ++timer;
	lca_util[i][0] = p;
	for(int j = 1;j<=l;j++){
		lca_util[i][j] = lca_util[lca_util[i][j - 1]][j - 1];
	}
	for(int e : adj[i]){
		if(e != p){
			dfs(e,i);
		}	
	}
	tout[i] = ++timer;
}
bool is_ancestor(int i,int j){
	return (tin[i] <= tin[j] && tout[i] >= tin[j]);
}
int lca(int u, int v){
    if (is_ancestor(u, v))
        return u;
    if (is_ancestor(v, u))
        return v;
    for (int i = l; i >= 0; --i) {
        if (!is_ancestor(lca_util[u][i], v))
            u = lca_util[u][i];
    }
    return lca_util[u][0];
}
void dfs2(int i,int p){
	for(int e : adj[i]){
		if(e != p){
			dist[e] = dist[i] + 1;
			dfs2(e,i);
			ans[i] += ans[e];
		}
	}
}
signed main(){
	iostream::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> m >> k;
	l = ceil(log2(n)) + 1;
	for(int i = 0;i<n-1;i++){
		int a,b;cin >> a >> b;
		a--;b--;
		edges.push_back({a,b});
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	dfs(0,0);
	for(int __ = 0;__ < m;__++){
		int siz;cin >> siz;
		vector<int> vec(siz);
		for(int &e : vec){
			cin >> e;
			e--;
		}
		sort(vec.begin(),vec.end(),[&](int i,int j){
			return tin[i] < tin[j];
		});
		for(int i = 0;i<vec.size();i++){
			int ll = lca(vec[i], vec[(i + 1)%siz]);
			// cout << vec[i] << " " << vec[(i + 1)%siz] << " " << ll << "\n";
			ans[vec[i]]++;
			ans[vec[(i + 1)%siz]]++;
			ans[ll] -= 2;
		}
	}
	dist[0] = 0;
	dfs2(0,0);
	for(int i = 0;i<n;i++)
		cout << ans[i] << " ";
	cout << "\n";
	vector<int> temp;
	for(int i = 0;i<n - 1;i++){
		int asd = edges[i].first;
		if(dist[asd] < dist[edges[i].second])
			asd =edges[i].second;
		if(ans[asd] >= 2*k)
			temp.push_back(i);
	}
	cout << temp.size() << "\n";
	for(int &e : temp)
		cout << e + 1 << " ";
	cout << "\n";
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:71:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |   for(int i = 0;i<vec.size();i++){
      |                 ~^~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 15
• Subtask 3: 0 / 7
• Subtask 4: 0 / 29
• Subtask 5: 0 / 16
• Subtask 6: 0 / 25