Submission #163207

#	Time	Username	Problem	Language	Result	Execution time	Memory
163207		Minnakhmetov	Railway (BOI17_railway)	C++14	100 / 100	149 ms	23852 KiB

railway

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

struct E {
	int to, i;
};

const int N = 1e5 + 5, L = 19;
int tin[N], tout[N], p[N][L], w[N];
int n, m, k, timer = 0;
vector<E> g[N];
vector<int> ans;

void dfs(int node) {
	tin[node] = ++timer;
	for (int i = 1; i < L; i++) {
		p[node][i] = p[p[node][i - 1]][i - 1];
	}
	for (E e : g[node]) {
		if (e.to != p[node][0]) {
			p[e.to][0] = node;
			dfs(e.to);
		}
	}
	tout[node] = timer;
}

void dive(int node) {
	for (E e : g[node]) {
		if (e.to != p[node][0]) {
			dive(e.to);
			if (w[e.to] >= k)
				ans.push_back(e.i);
			w[node] += w[e.to];
		}
	}
}

bool upper(int a, int b) {
	return tin[a] <= tin[b] && tout[a] >= tout[b];
}

int getLca(int a, int b) {
	if (upper(a, b))
		return a;
	for (int i = L - 1; i >= 0; i--) {
		if (!upper(p[a][i], b))
			a = p[a][i];
	}
	return p[a][0];
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);

    cin >> n >> m >> k;

    for (int i = 0; i < n - 1; i++) {
    	int a, b;
    	cin >> a >> b;
    	a--, b--;
    	g[a].push_back({b, i});
    	g[b].push_back({a, i});
    }

    dfs(0);

    for (int i = 0; i < m; i++) {
    	int s;
    	cin >> s;

    	vector<int> v;

    	for (int j = 0; j < s; j++) {
    		int x;
    		cin >> x;
    		v.push_back(x - 1);
    	}

    	sort(all(v), [](int x, int y) {
    		return tin[x] < tin[y];
    	});

    	for (int j = 0; j < v.size(); j++) {
    		int h = (j + 1 == v.size() ? 0 : j + 1),
    			lca = getLca(v[j], v[h]);
    		w[v[j]]++;
    		w[lca]--;
    	}
    }

    dive(0);

    cout << ans.size() << "\n";

    sort(all(ans));
    for (int x : ans)
    	cout << x + 1 << " ";

    return 0;
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:89:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for (int j = 0; j < v.size(); j++) {
                      ~~^~~~~~~~~~
railway.cpp:90:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       int h = (j + 1 == v.size() ? 0 : j + 1),
                ~~~~~~^~~~~~~~~~~

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