Submission #441481

#	Time	Username	Problem	Language	Result	Execution time	Memory
441481		8e7	From Hacks to Snitches (BOI21_watchmen)	C++14	0 / 100	68 ms	10860 KiB

watchmen

//Challenge: Accepted
#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
#include <queue>
#include <set>
//#include <ext/pb_ds/assoc_contatiner.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
void debug() {cout << endl;}
template<class T, class ... U> void debug(T a, U ... b) { cout << a << " ";debug(b...);}
template<class T> void pary (T l, T r) {
	while (l != r) cout << (*l) << " ", l++;
	cout << endl;
}
#define ll long long
#define maxn 200005
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
const ll inf = 1LL<<60;
vector<int> adj[maxn];
pii res[maxn];
ll dis[maxn];
int main() {
	io
	int n, m;
	cin >> n >> m;
	for (int i = 0;i < m;i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	for (int i = 1;i <= n;i++) res[i] = {1, 1}, dis[i] = inf;
	int k;
	cin >> k;
	for (int i = 0;i < k;i++) {
		int li;
		cin >> li;
		for (int j = 0;j < li;j++) {
			int x;
			cin >> x;
			res[x] = {j, li};
		}
	}
	queue<pii> que;
	dis[1] = 0;
	que.push({1, 0});
	while (que.size()) {
		int cur = que.front().ff;
		ll d = que.front().ss;
		que.pop();
		//debug(49, cur, d);
		if (d != dis[cur]) continue;
		for (int v:adj[cur]) {
			int w = 1;	
			if ((d + 1) % res[cur].ss == res[cur].ff && d % res[v].ss == res[v].ff) {
				//debug(n, v);
				continue; // can't go through this edge
			}
			if ((d + 1) % res[v].ss == res[v].ff) w = 2;
			if (d + w < dis[v]) {
				//debug(14, v, d + w);
				dis[v] = d + w;
				que.push({v, dis[v]});	
			}
		}
	}	
	cout << dis[n] << "\n";
}
/*
6 6
1 2
2 3
3 4
4 5
5 2
5 6
1
4 3 2 5 4
*/

• Subtask 1: 0 / 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