Submission #378643

#	Time	Username	Problem	Language	Result	Execution time	Memory
378643		8e7	Evacuation plan (IZhO18_plan)	C++14	100 / 100	823 ms	64604 KiB

plan

//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
#include <queue>
#define ll long long
#define maxn 200005
#define pii pair<int, ll>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
const ll inf = 1LL<<60;
vector<pii> adj[maxn / 2], ord;
vector<int> tree[maxn];
int anc[18][maxn], dep[maxn];
ll mind[maxn];
int par[maxn];
bool done[maxn];

inline bool cmp(const pii & a, const pii & b) {
	return a.ss > b.ss;
}
priority_queue<pii, vector<pii>, bool (*) (const pii &, const pii &) > pq(cmp);

int find(int a) {
	return a == par[a] ? a : par[a] = find(par[a]);
}

void dfs(int n, int par, int d) {
	anc[0][n] = par;
	dep[n] = d;
	for (int v:tree[n]) {
		if (v != par) {
			dfs(v, n, d + 1);
		}
	}
}
int lca(int a, int b) {
	if (dep[a] < dep[b]) swap(a, b);
	int hdif = dep[a] - dep[b], cnt = 0;
	while (hdif) {
		if (hdif & 1) {
			a = anc[cnt][a];
		}
		cnt++, hdif >>= 1;
	}
	if (a == b) return a;
	for (int i = 17;i >= 0;i--) {
		if (anc[i][a] != anc[i][b]) {
			a = anc[i][a], b = anc[i][b];
		}
	}
	return anc[0][a];
}
int main() {
	io
	int n, m;
	cin >> n >> m;
	for (int i = 1;i < maxn;i++) mind[i] = inf, par[i] = i;
	for (int i = 0;i < m;i++) {
		int a, b, w;
		cin >> a >> b >> w;
		adj[a].push_back(make_pair(b, w));
		adj[b].push_back(make_pair(a, w));
	}

	int k;
	cin >> k;
	for (int i = 0;i < k;i++) {
		int gi;
		cin >> gi;
		mind[gi] = 0;
		pq.push(make_pair(gi, 0));
	}
	while (pq.size()) {
		int cur = pq.top().ff;
		ll dis = pq.top().ss;
		pq.pop();
		if (dis != mind[cur]) continue;
		for (auto v:adj[cur]) {
			ll nd = v.ss + mind[cur];
			if (nd < mind[v.ff]) {
				mind[v.ff] = nd;
				pq.push(make_pair(v.ff, nd));
			}
		}
	}
	for (int i = 1;i <= n;i++) {
		ord.push_back(make_pair(i, mind[i]));
		//cout << mind[i] << " ";
	}
	//cout << endl;
	sort(ord.begin(), ord.end(), cmp);

	int cur = n + 1;
	for (int i = 0;i < n;i++) {

		for (auto v:adj[ord[i].ff]) {
			if (!done[v.ff]) continue;
			int a = find(ord[i].ff), b = find(v.ff);
			if (a != b) {
				//cout << ord[i].ff << " " << v.ff << endl;
				mind[cur] = min(mind[a], mind[b]);
				tree[cur].push_back(a);
				tree[a].push_back(cur);

				tree[cur].push_back(b);
				tree[b].push_back(cur);
				par[a] = cur, par[b] = cur;
				cur++;
			}
		}
		done[ord[i].ff] = true;
	}
	dfs(cur - 1, 0, 0);
	for (int i = 1;i < 18;i++) {
		for (int j = 1;j < cur;j++) anc[i][j] = anc[i - 1][anc[i - 1][j]];
	}


	int q;
	cin >> q;
	for (int i = 0;i < q;i++) {
		int a, b;
		cin >> a >> b;
		cout << mind[lca(a, b)] << "\n";
	}

}
/*
9 12
1 9 4
1 2 5
2 3 7
2 4 3
4 3 6
3 6 4
8 7 10
6 7 5
5 8 1
9 5 7
5 4 12
6 8 2
2
4 7
5
1 6
5 3
4 8
5 8
1 5
 */

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