Submission #258687

#	Time	Username	Problem	Language	Result	Execution time	Memory
258687		vioalbert	Cities (BOI16_cities)	C++14	100 / 100	1230 ms	36448 KiB

cities

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
using state = pair<ll, int>;

const ll N = 1e5+5, INF = 1e18;
ll ans = INF;
int n, m, k;
vector<pair<int, ll>> adj[N];
vector<int> must;
ll dp[16][N];

int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n >> k >> m;
	for(int i = 0; i < k; i++) {
		int x; cin >> x;
		must.push_back(x);
	}
	k--;
	for(int i = 0; i < m; i++) {
		ll u, v, w; cin >> u >> v >> w;
		adj[u].push_back({v, w});
		adj[v].push_back({u, w});
	}

	for(int mask = 0; mask < 16; mask++) {
		for(int i = 1; i <= n; i++) {
			if(mask == 0) dp[mask][i] = 0;
			else dp[mask][i] = INF;
		}
	}

	for(int i = 0; i < k; i++)
		dp[(1<<i)][must[i]] = 0;

	for(int mask = 0; mask < (1<<k); mask++) {
		priority_queue<state, vector<state>, greater<state>> pq;
		for(int i = 1; i <= n; i++) {
			for(int sub = mask; sub > 0; sub = (sub - 1) & mask)
				dp[mask][i] = min(dp[mask][i], dp[sub][i] + dp[mask^sub][i]);
			pq.push({dp[mask][i], i});
		}

		while(!pq.empty()) {
			ll dt = pq.top().first; int i = pq.top().second; pq.pop();
			if(dt > dp[mask][i]) continue;
			for(auto& it : adj[i]) {
				if(dp[mask][it.first] > dp[mask][i] + it.second) {
					dp[mask][it.first] = dp[mask][i] + it.second;
					pq.push({dp[mask][it.first], it.first});
				}
			}
		}
	}

	cout << dp[(1<<k)-1][must[k]] << '\n';
	return 0;
}

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