Submission #379948

#	Time	Username	Problem	Language	Result	Execution time	Memory
379948		nikatamliani	Relay Marathon (NOI20_relaymarathon)	C++14	100 / 100	2098 ms	135576 KiB

RelayMarathon

#include <bits/stdc++.h>
using namespace std;
int n, m, k;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int a, int b) {
	return a + (unsigned long long)rng() % (b - a + 1);
}
const int oo = 1e9+10;
int calc(vector<int> &a, vector<int> &b, vector<vector<pair<int, int>>> &edges) {
	priority_queue<pair<int,int>> q;
	for(int x : a) {
		q.push({0, x});
	}
	vector<bool> fix(n), seen(n);
	for(int x : b) {
		fix[x] = 1;
	}
	while(!q.empty()) {
		pair<int,int> p = q.top(); q.pop();
		if(fix[p.second]) return -p.first;
		if(seen[p.second]) continue;
		seen[p.second] = 1;
		for(const pair<int,int> &to : edges[p.second]) {
			if(!seen[to.first]) {
				q.push({p.first - to.second, to.first});
			}
		}
	}
	return oo;
}
int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n >> m >> k;
	vector<vector<pair<int, int>>> edges(n);
	for(int i = 0; i < m; ++i) {
		int u, v, w;
		cin >> u >> v >> w; --u, --v; 
		edges[u].push_back({v, w});
		edges[v].push_back({u, w});
	}
	vector<int> special(k);
	for(int &i : special) cin >> i, --i;
	int ans = oo;
	for(clock_t it = clock(); it < 2 * CLOCKS_PER_SEC; it = clock()) {
		shuffle(special.begin(), special.end(), rng);
		vector<int> start[2], end[2];
		for(int i = 0; i < k / 2; ++i) {
			start[rng() & 1].push_back(special[i]);
		}
		for(int i = k / 2; i < k; ++i) {
			end[rng() & 1].push_back(special[i]);
		}
		ans = min(ans, calc(start[0], end[0], edges) + calc(start[1], end[1], edges));
	}
	cout << ans << '\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 25 / 25
• Subtask 4: 58 / 58