Submission #586778

#	Time	Username	Problem	Language	Result	Execution time	Memory
586778		blue	Valley (BOI19_valley)	C++17	23 / 100	140 ms	20452 KiB

valley

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;
using ll = long long;
using vll = vector<ll>;
#define sz(x) int(x.size())

const int mx = 100'001;
const ll inf = 1'000'000'000'000'000'000LL;

int N, S, Q, E;

vi A(1+mx), B(1+mx);
vll W(1+mx);
vi edgeind[1+mx];

vll nearshop(1+mx, inf); //distance to closest shop within subtree


vi parent(1+mx, 0);
vi paredge(1+mx, 0);
vll distE(1+mx, 0);
vi depth(1+mx, 0);

vi edgelower(1+mx, 0);

int dfsct = 0;
vi dfsind(1+mx, 0);
vi subtree(1+mx, 1);

void dfs(int u, int p)
{
	dfsct++;
	dfsind[u] = dfsct;

	for(int e : edgeind[u])
	{
		int v = A[e] + B[e] - u;
		ll w = W[e];

		if(v == p)
			continue;

		parent[v] = u;
		paredge[v] = e;
		edgelower[e] = v;

		distE[v] = distE[u] + w;
		depth[v] = depth[u] + 1;

		dfs(v, u);

		nearshop[u] = min(nearshop[u], nearshop[v] + w);

		subtree[u] += subtree[v];
	}
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	cin >> N >> S >> Q >> E;

	for(int e = 1; e <= N-1; e++)
	{
		cin >> A[e] >> B[e] >> W[e];
		edgeind[A[e]].push_back(e);
		edgeind[B[e]].push_back(e);
	}

	for(int x = 1; x <= S; x++)
	{
		int u;
		cin >> u;
		nearshop[u] = 0;
	}

	dfs(E, 0);


	for(int q = 1; q <= Q; q++)
	{
		int I, R;
		cin >> I >> R;

		bool escape;

		if(R == E)
			escape = 1;
		else
		{
			int A = edgelower[I];
			if(dfsind[A] <= dfsind[R] && dfsind[R] < dfsind[A] + subtree[A])
				escape = 0;
			else
				escape = 1;
		}

		if(escape)
			cout << "escaped\n";
		else
			cout << 0 << '\n';
	}
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 27
• Subtask 3: 23 / 23
• Subtask 4: 0 / 41