Submission #972880

#	Time	Username	Problem	Language	Result	Execution time	Memory
972880		dio_2	Synchronization (JOI13_synchronization)	C++17	0 / 100	8042 ms	16944 KiB

synchronization

#include<bits/stdc++.h>
using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n, m, q;
	cin >> n >> m >> q;
	
	vector<vector<int>> g(n + 1);
	vector<pair<int, int>> kraw(n);
	vector<int> state_kraw(n); // na poczatky wszytko jest off.
	
	for(int i = 0;i < n - 1;i++){
		int a, b;
		cin >> a >> b;
		g[a].push_back(b);
		g[b].push_back(a);
		kraw[i + 1] = make_pair(a, b);
	}
	
	vector<int> dep(n + 1), tin(n + 1), tout(n + 1);
	vector<int> parent(n + 1), parent_kraw(n + 1);
	vector<int> passed_cnt(n + 1); // ile przeszlo od danej krawedzi
	vector<int> info(n + 1, 1); // ile informacij ma dane korzenie ( czyli leader DSU )
	int T = 1;
	auto dfs1 = [&](auto &&dfs1, int u, int p)->void{
		tin[u] = T++;
		for(int v : g[u]) if(v != p){
			parent[v] = u;
			dep[v] = dep[u] + 1;
			dfs1(dfs1, v, u);
		}
		tout[u] = T++;
	}; dfs1(dfs1, 1, 0);
	
	for(int i = 1;i <= n - 1;i++){
		auto [a, b] = kraw[i];
		if(dep[a] > dep[b]) swap(a, b);
		parent_kraw[b] = i;
	}
	
	while(m--){
		int e;
		cin >> e;
		
		auto [a, b] = kraw[e];
		if(dep[a] > dep[b]) swap(a, b);
		// a na gorze
		
		if(!state_kraw[e]){ // polacz 
			// b jest korzeniem dolnego poddrzewa
			// dla a nie wiemy kim jest leaderem treba isc do gory do poki mozna
			int leader1 = b;
			int leader2 = a;
			while(parent[a] and state_kraw[ parent_kraw[a] ] ) a = parent[a]; // this is the bottle-neck.
			leader2 = a;
			// leader2 bedzie tez na koncu leader
			
			int przejdzie = info[leader1] - passed_cnt[e];
			info[leader2] += przejdzie;
			passed_cnt[e] += przejdzie;
		} else { // rozlacz
			int leader1 = b;
			int leader2 = a;
			while(parent[a] and state_kraw[ parent_kraw[a] ] ) a = parent[a];
			leader2 = a;
			// teraz bedziemy miec leader2 i leader1
			info[leader1] = info[leader2];
		}
		
		state_kraw[e] ^= 1;
	}
	
	for(int i = 0;i < q;i++){
		int a;
		cin >> a;
		while(parent[a] and state_kraw[ parent_kraw[a] ] ) a = parent[a];
		cout << info[a] << '\n';                              
	}
	
	return 0;	
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 10
• Subtask 4: 0 / 20
• Subtask 5: 0 / 40