Submission #693678

#	Time	Username	Problem	Language	Result	Execution time	Memory
693678		ajab_01	Cities (BOI16_cities)	C++17	0 / 100	879 ms	262144 KiB

cities

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

const int N = 1e5 + 5;
const int LOG = 20;
vector<pair<int , int> > g[N] , adj[N];
vector<pair<int , pair<int , int> > > edge;
vector<int> vec;
int jad[N][LOG] , level[N] , sz[N] , par[N] , val[N] , lc = -1 , n , k , m;
bool vis[N];
long long ans;

int get(int u){
	if(u != par[u]) par[u] = get(par[u]);
	return par[u];
}

void merge(int u , int v){
	if(sz[u] < sz[v])
		swap(u , v);
	sz[u] += sz[v];
	par[v] = u;
}

void find_mst(){
	for(int i = 1 ; i <= n ; i++){
		sz[i] = 1;
		par[i] = i;
	}

	sort(edge.begin() , edge.end());

	for(auto x : edge){
		int u = x.second.first , v = x.second.second , w = x.first;
		if(get(u) != get(v)){
			merge(u , v);
			adj[u].push_back({v , w});
			adj[v].push_back({u , w});
		}
	}
}

void dfs(int ver , int pr){
	for(auto j : adj[ver]){
		int i = j.first;
		if(i == pr) continue;
		level[i] = level[ver] + 1;
		jad[i][0] = ver;
		for(int k = 1 ; k < LOG ; k++)
			jad[i][k] = jad[jad[i][k - 1]][k - 1];
		dfs(i , ver);
	}
}

int lca(int u , int v){
	if(level[u] > level[v])
		swap(u , v);

	int dis = level[v] - level[u];
	for(int i = LOG - 1 ; i >= 0 ; i--)
		if(dis & (1 << i))
			v = jad[v][i];

	if(v == u)
		return v;

	for(int i = LOG - 1 ; i >= 0 ; i--){
		if(jad[v][i] != jad[u][i]){
			u = jad[u][i];
			v = jad[v][i];
		}
	}

	return jad[v][0];
}

void cal(int ver , int pr){
	for(auto j : adj[ver]){
		int i = j.first , w = j.second;
		if(i == pr) continue;
		val[i] = w;
		par[i] = ver;
		cal(i , ver);
	}
}

int main(){
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> k >> m;
	for(int i = 0 ; i < k ; i++){
		int vertex;
		cin >> vertex;
		vec.push_back(vertex);
	}

	for(int i = 0 ; i < m ; i++){
		int u , v , w;
		cin >> u >> v >> w;
		g[u].push_back({v , w});
		g[v].push_back({u , w});
		edge.push_back({w , {u , v}});
	}

	find_mst();

	dfs(1 , 0);

	for(int i : vec){
		if(lc == -1){
			lc = i;
			continue;
		}

		lc = lca(lc , i);
	}

	cal(1 , 0);

	for(int i : vec){
		int vertex = i;
		while(vertex != lc){
			vis[vertex] = 1;
			vertex = par[vertex];
		}
	}

	for(int i = 2 ; i <= n ; i++)
		if(vis[i])
			ans += val[i];

	cout << ans << '\n';
	return 0;
}

• Subtask 1: 0 / 22
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 26