Submission #405999

#	Time	Username	Problem	Language	Result	Execution time	Memory
405999		maomao90	From Hacks to Snitches (BOI21_watchmen)	C++17	0 / 100	6088 ms	18376 KiB

watchmen

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

#define mnto(x, y) x = min(x, (__typeof__(x)) y)
#define mxto(x, y) x = max(x, (__typeof__(x)) y)
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define MT make_tuple
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb emplace_back
typedef vector<int> vi;
typedef vector<ii> vii;

#define INF 1000000005
#define LINF 1000000000000000005
#define MOD 1000000007
#define MAXN 200005
#define MAXK 1000
#define MAXL 1505

struct edge {
	int v;
	vii res;
	edge() {}
	edge(int v): v(v) {}
};

int n, m;
vector<edge> adj[MAXN];
int k;
int l[MAXK];
int arr[MAXK][MAXL];
edge inv[MAXN];
priority_queue<pll, vector<pll>, greater<pll>> pq;
ll dist[MAXN];

int main() {
	scanf("%d%d", &n, &m);
	REP (i, 0, m) {
		int u, v; scanf("%d%d", &u, &v);
		adj[u].pb(edge(v));
		adj[v].pb(edge(u));
	}
	scanf("%d", &k);
	REP (i, 0, k) {
		scanf("%d", &l[i]);
		REP (j, 0, l[i]) {
			scanf("%d", &arr[i][j]);
		}
		REP (j, 0, l[i]) {
			int v = arr[i][j], u = arr[i][(j + 1) % l[i]];
			for (edge &e : adj[u]) {
				if (e.v == v) {
					e.res.pb(l[i], j);
				}
			}
			inv[v] = edge();
			inv[v].res.pb(l[i], j);
		}
	}
	REP (i, 1, n + 1) {
		dist[i] = LINF;
	}
	dist[1] = 0;
	pq.push(MP(0, 1));
	while (!pq.empty()) {
		auto [ud, u] = pq.top(); pq.pop();
		if (dist[u] != ud) continue;
		int cnt = 0;
		for (edge e : adj[u]) {
			bool pos = 1;
			for (auto [mod, rem] : e.res) {
				if (ud % mod == rem) pos = 0;
			}
			if (!pos) {
				cnt++;
			   	continue;
			}
			ll vd = ud + 1;
			bool poss = 1;
			for (auto [mod, rem] : inv[e.v].res) {
				if (vd % mod == rem) poss = 0;
			}
			if (!poss) {
				cnt++;
			   	continue;
			}
			//if (!poss) {
				//bool posss = 1;
				//for (auto [mod, rem] : inv[u].res) {
					//if ((ud + 1) % mod == rem) posss = 0;
				//}
				//if (posss) vd = ud + 2;
				//else vd = LINF;
			//}
			if (vd < dist[e.v]) {
				//printf("%lld -> %d: %lld %lld\n", u, e.v, ud, vd);
				dist[e.v] = vd;
				pq.push(MP(vd, e.v));
			}
		}
		if (cnt == 0) continue;
		bool posss = 1;
		for (auto [mod, rem] : inv[u].res) {
			if ((ud + 1) % mod == rem) posss = 0;
		}
		if (posss) {
			dist[u] = ++ud;
			pq.push(MP(ud, u));
		}
	}
	if (dist[n] == LINF) {
		printf("impossible\n");
	} else {
		printf("%lld\n", dist[n]);
	}
	return 0;
}

/*
6 6                            
1 2
2 3
3 4
4 5
5 2
5 6
1
4 3 2 5 4

6 6
1 2
2 3
3 4
4 5
5 2
5 6
1
4 4 5 2 3

11 13
1 2
2 3
3 4
4 2
3 5
5 6
6 7
7 5
6 8
8 9
9 10
10 8
9 11
3
3 4 2 3
3 7 6 5
3 10 8 9
*/

Compilation message (stderr)

watchmen.cpp: In function 'int main()':
watchmen.cpp:46:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
watchmen.cpp:48:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |   int u, v; scanf("%d%d", &u, &v);
      |             ~~~~~^~~~~~~~~~~~~~~~
watchmen.cpp:52:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |  scanf("%d", &k);
      |  ~~~~~^~~~~~~~~~
watchmen.cpp:54:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |   scanf("%d", &l[i]);
      |   ~~~~~^~~~~~~~~~~~~
watchmen.cpp:56:9: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |    scanf("%d", &arr[i][j]);
      |    ~~~~~^~~~~~~~~~~~~~~~~~
watchmen.cpp:29:8: warning: '<anonymous>.edge::v' may be used uninitialized in this function [-Wmaybe-uninitialized]
   29 | struct edge {
      |        ^~~~

• 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