Submission #37330

#	Time	Username	Problem	Language	Result	Execution time	Memory
37330		szawinis	Cities (BOI16_cities)	C++14	100 / 100	3069 ms	41916 KiB

cities

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, int> pli;
const int N = 1e5+1;
const ll INF = 1e17+1;

int n, k, m;
bool mark[N];
vector<int> s;
vector<pair<int,int> > g[N];
ll ans = INF, dp[1 << 5][N];
priority_queue<pli, vector<pli>, greater<pli> > pq;
int main() {
	scanf("%d %d %d", &n, &k, &m);
	for(int i = 0, v; i < k; i++) {
		scanf("%d", &v);
		s.push_back(v-1);
	}

	for(int i = 0, u, v, w; i < m; i++) {
		scanf("%d %d %d", &u, &v, &w);
		g[u-1].emplace_back(v-1, w);
		g[v-1].emplace_back(u-1, w);
	}

	for(int mask = 1; mask < 1 << k; mask++) {
		for(int v = 0; v < n; v++) dp[mask][v] = INF;
	}
	for(int i = 0; i < k; i++) dp[1 << i][s[i]] = 0;

	for(int mask = 1; mask < 1 << k; mask++) {
		for(int prev_mask1 = 1; prev_mask1 < mask; prev_mask1++) {
			int prev_mask2 = prev_mask1 ^ mask;
			if((prev_mask1 | mask) != mask || prev_mask2 > prev_mask1) continue;
			for(int v = 0; v < n; v++)
				dp[mask][v] = min(dp[prev_mask1][v] + dp[prev_mask2][v], dp[mask][v]);
		}
		for(int v = 0; v < n; v++) if(dp[mask][v] < INF) pq.emplace(dp[mask][v], v);
		fill(mark, mark+n, 0);
		while(!pq.empty()) {
			int u = pq.top().second;
			pq.pop();
			if(mark[u]) continue;
			mark[u] = true;
			for(auto p: g[u]) if(dp[mask][u] + p.second < dp[mask][p.first]) {
				dp[mask][p.first] = dp[mask][u] + p.second;
				pq.emplace(dp[mask][p.first], p.first);
			}
		}
	}
	ll ans = INF;
	for(int v = 0; v < n; v++) ans = min(dp[(1 << k)-1][v], ans);
	printf("%lld", ans);
}

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:15:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &n, &k, &m);
                               ^
cities.cpp:17:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &v);
                  ^
cities.cpp:22:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d", &u, &v, &w);
                                ^

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