Submission #147326

#	Time	Username	Problem	Language	Result	Execution time	Memory
147326		cerberus	Cities (BOI16_cities)	C++17	100 / 100	4997 ms	164824 KiB

cities

/* cerberus97 - Hanit Banga */

#include <iostream>
#include <iomanip>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <vector>
#include <algorithm>

using namespace std;

#define pb push_back
#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL)

typedef long long ll;
typedef long double ld;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

const int N = 1e5 + 10, K = 5, S = (1 << K) + 10;
const ll inf = 1e15 + 42;

struct state_t {
	int mask, u;
	ll val;
	bool operator<(const state_t &o) const {
		return val > o.val;
	}
};

int imp[K];
vector<pii> g[N];
vector<int> supermasks[S];
ll dp[S][N];

int main() {
	fast_cin();
	int n, k, m;
	cin >> n >> k >> m;
	for (int i = 0; i < k; ++i) {
		cin >> imp[i];
	}
	for (int i = 0; i < m; ++i) {
		int u, v, w;
		cin >> u >> v >> w;
		g[u].pb({v, w});
		g[v].pb({u, w});
	}
	int tot = (1 << k), all = tot - 1;
	for (int mask = 1; mask < tot; ++mask) {
		for (int u = 1; u <= n; ++u) {
			dp[mask][u] = inf;
		}
	}
	for (int mask = 0; mask < tot; ++mask) {
		if (true) {
		// if (__builtin_popcount(mask) <= 1) {
			for (int smask = mask + 1; smask < tot; ++smask) {
				if ((smask & mask) == mask) {
					supermasks[mask].pb(smask);
				}
			}
		} else {
			for (int i = 0; i < k; ++i) {
				if (!(mask & (1 << i))) {
					supermasks[mask].pb(mask | (1 << i));
				}
			}
		}
	}
	priority_queue<state_t> q;
	for (int i = 0; i < k; ++i) {
		dp[1 << i][imp[i]] = 0;
		q.push({1 << i, imp[i], 0});
	}
	while (!q.empty()) {
		auto cur = q.top();
		q.pop();
		int mask = cur.mask, u = cur.u;
		if (dp[mask][u] != cur.val) {
			continue;
		}
		if (mask == all) {
			cout << dp[mask][u] << endl;
			return 0;
		}
		for (auto &e : g[u]) {
			int v = e.first, w = e.second;
			ll cand = dp[mask][u] + w;
			if (cand < dp[mask][v]) {
				dp[mask][v] = cand;
				q.push({mask, v, cand});
			}
		}
		for (auto &nmask : supermasks[mask]) {
			int extra = nmask ^ mask;
			ll cand = dp[mask][u] + dp[extra][u];
			if (cand < dp[nmask][u]) {
				dp[nmask][u] = cand;
				q.push({nmask, u, cand});
			}
		}
	}
}

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