Submission #633181

#	Time	Username	Problem	Language	Result	Execution time	Memory
633181		Alma	Valley (BOI19_valley)	C++17	36 / 100	3097 ms	9816 KiB

valley

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
using ll = long long;
using ii = pair<int,int>;

const int INF = 1e9;
const ll LLINF = 1e18;
using vi = vector<int>;
using vvi = vector<vi>;

void setIO (string fileName) {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    if (fileName != "std") {
        freopen((fileName + ".in").c_str(), "r", stdin);
        freopen((fileName + ".out").c_str(), "w", stdout);
    }
}

struct edge {
	int a, b, c;
};

vector<ll> dijkstra (int n, int s, vector<vector<ii>>& adj) {
	vector<ll> dist(n, LLINF);
	dist[s] = 0;
	priority_queue<pair<ll, int>> pq;
	pq.push({0, s});

	while (!pq.empty()) {
		int u = pq.top().second;
		ll d = -pq.top().first;
		pq.pop();
		if (d > dist[u]) continue;
		for (ii p: adj[u]) {
			int v = p.fi, c = p.se;
			if (d + c < dist[v]) {
				dist[v] = d+c;
				pq.push({-d-c, v});
			}
		}
	}
	return dist;
}

int main() {
    setIO("std");

    int n, s, q, e;
	cin >> n >> s >> q >> e;
	e--;
	vector<edge> list(n-1);
	for (int i = 0; i < n-1; i++) {
		cin >> list[i].a >> list[i].b >> list[i].c;
		list[i].a--;
		list[i].b--;
	}
	int x, y;
	vector<bool> shop(n, false);
	for (int i = 0; i < s; i++) {
		cin >> x;
		shop[x-1] = true;
	}
	while (q--) {
		cin >> x >> y;
		x--; y--;
		vector<vector<ii>> adj(n);
		for (int i = 0; i < n-1; i++) {
			if (i == x) continue;
			adj[list[i].a].push_back({list[i].b, list[i].c});
			adj[list[i].b].push_back({list[i].a, list[i].c});
		}
		vector<ll> dist = dijkstra(n, y, adj);
		if (dist[e] != LLINF) {
			cout << "escaped\n";
		} else {
			ll ans = LLINF;
			for (int i = 0; i < n; i++) {
				if (shop[i] and dist[i] != LLINF) {
					ans = min(ans, dist[i]);
				}
			}
			if (ans == LLINF) cout << "oo\n";
			else cout << ans << '\n';
		}
	}

    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void setIO(std::string)':
valley.cpp:18:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |         freopen((fileName + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:19:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         freopen((fileName + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 0 / 23
• Subtask 4: 0 / 41