Submission #287374

#	Time	Username	Problem	Language	Result	Execution time	Memory
287374		Berted	Evacuation plan (IZhO18_plan)	C++14	100 / 100	766 ms	46956 KiB

plan

#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#include <assert.h>
#define pii pair<int, int>
#define vi vector<int>
#define vpi vector<pii>
#define fst first
#define snd second
using namespace std;

const int INF = 1e9, LG = 17;

int n, m, k, q;
vpi adj[100001];
vi tree[100001];
int dist[100001], par[100001], h[100001], sps[100001][LG][2];
vpi ord;
priority_queue<pii, vector<pii>, greater<pii>> pq;

void runDijkstra()
{
	while (pq.size())
	{
		int u = pq.top().snd, d = pq.top().fst; pq.pop();
		//cout << "DIST : " << u << " " << dist[u] << "\n";
		if (dist[u] == d)
		{
			for (auto v : adj[u])
			{
				if (dist[u] + v.snd < dist[v.fst])
				{
					dist[v.fst] = dist[u] + v.snd;
					pq.push({dist[v.fst], v.fst});
				}
			}
		}
	}
}

int fn(int x) {return par[x] = (par[x] == x) ? x : fn(par[x]);}
void jn(int a, int b)
{
	int oa = fn(a), ob = fn(b);
	if (oa != ob)
	{
		par[ob] = oa;
		tree[a].push_back(b);
		tree[b].push_back(a);
	}
}

void DFS(int u, int p, int val)
{
	sps[u][0][0] = p; sps[u][0][1] = val; h[u] = (p == -1) ? 0 : (h[p] + 1);
	for (int i = 1; i < LG; i++)
	{
		if (sps[u][i - 1][0] != -1)
		{
			sps[u][i][0] = sps[sps[u][i - 1][0]][i - 1][0];
			sps[u][i][1] = min(sps[u][i - 1][1], sps[sps[u][i - 1][0]][i - 1][1]);
		}
		else {sps[u][i][0] = -1; sps[u][i][1] = INF;}
	}
	for (auto v : tree[u])
	{
		if (v != p) {DFS(v, u, dist[u]);}
	}
}

int getAnswer(int u, int v)
{
	int res = min(dist[u], dist[v]);
	if (h[u] > h[v]) {swap(v, u);}
	for (int i = 0; h[v] - h[u]; i++)
	{
		if ((h[v] - h[u]) & (1 << i)) 
		{
			res = min(sps[v][i][1], res);
			v = sps[v][i][0];
		}
	}
	for (int i = LG - 1; i >= 0; i--)
	{
		if (sps[u][i][0] != sps[v][i][0])
		{
			res = min(res, min(sps[u][i][1], sps[v][i][1]));
			u = sps[u][i][0]; v = sps[v][i][0];
		}
	}
	if (u != v)
	{
		res = min(res, min(sps[u][0][1], sps[v][0][1]));
		u = sps[u][0][0];
		v = sps[v][0][0];
	}
	//assert(u == v);
	return res;
}

int main()
{
	ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> n >> m;
	for (int i = 0; i < n; i++) {dist[i] = INF; par[i] = -1;}
	for (int i = 0; i < m; i++)
	{
		int u, v, w; cin >> u >> v >> w;
		adj[u - 1].push_back({v - 1, w});
		adj[v - 1].push_back({u - 1, w});
	}
	cin >> k;
	for (int i = 0; i < k; i++)
	{
		int x; cin >> x; x--;
		dist[x] = 0; pq.push({0, x});
	}
	runDijkstra();
	for (int i = 0; i < n; i++) {ord.push_back({-dist[i], i});}
	sort(ord.begin(), ord.end());
	
	for (int i = 0; i < n; i++)
	{
		int u = ord[i].snd;
		par[u] = u;
		for (auto v : adj[u])
		{
			if (par[v.fst] != -1) {jn(v.fst, u);}
		}
	}
	DFS(0, -1, INF);
	cin >> q;
	for (int i = 0; i < q; i++)
	{
		int u, v; cin >> u >> v;
		cout << getAnswer(u - 1, v - 1) << "\n";
	}
	return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46