Submission #863877

#	Time	Username	Problem	Language	Result	Execution time	Memory
863877		TAhmed33	From Hacks to Snitches (BOI21_watchmen)	C++98	5 / 100	3074 ms	105720 KiB

watchmen

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int inf = 1e16;
int dist[100001][126];
int arr[126];
int n;
vector <int> adj[100001];
signed main () {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int m;
	cin >> n >> m;
	for (int i = 1; i <= m; i++) {
		int a, b;
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	int l; cin >> l >> l;
	for (int i = 0; i < l; i++) cin >> arr[i];
	for (int i = 0; i < 125; i++) {
		for (int j = 1; j <= n; j++) {
			dist[j][i] = inf;
		}
	}
	dist[1][0] = 0;
	priority_queue <vector <int>, vector <vector <int>>, greater <vector <int>>> pq;
	pq.push({0, 0, 1});
	while (!pq.empty()) {
		auto k = pq.top();
		pq.pop();
		if (arr[(k[1] + 1) % l] != k[2]) {
			if (dist[k[2]][(k[1] + 1) % l] > k[0] + 1) {
				dist[k[2]][(k[1] + 1) % l] = k[0] + 1;
				pq.push({k[0] + 1, (k[1] + 1) % l, k[2]});
			}
		}
		for (auto j : adj[k[2]]) {
			if (j == arr[(k[1] + 1) % l] || (j == arr[k[1]] && k[2] == arr[(k[1] + 1) % l])) continue;
			if (dist[j][(k[1] + 1) % l] > k[0] + 1) {
				dist[j][(k[1] + 1) % l] = k[0] + 1;
				pq.push({k[0] + 1, (k[1] + 1) % l, j});
			}
		}
	}
	int mn = inf;
	for (int i = 0; i < l; i++) {
		mn = min(mn, dist[n][i]);
	}
	if (mn >= inf) cout << "impossible\n";
	else cout << mn << '\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20