Submission #409035

#	Time	Username	Problem	Language	Result	Execution time	Memory
409035		Kevin_Zhang_TW	From Hacks to Snitches (BOI21_watchmen)	C++17	15 / 100	6039 ms	81772 KiB

watchmen

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
void debug(auto l, auto r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

using t3 = pair<ll,int>;
const int MAX_N = 300010, MAX_K = 2800, hol = 100;
const ll inf = 1ll << 55;

int n, m;
vector<int> edge[MAX_N], cyc[MAX_N];
vector<ll> dp[MAX_N];
int cid[MAX_N], csz[MAX_N], cpos[MAX_N];

int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> m;
	for (int a, b, i = 0;i < m;++i) {
		cin >> a >> b;
		edge[a].pb(b);
		edge[b].pb(a);
	}
	for (int i = 1;i <= n;++i) {
		dp[i].resize(1, inf);
		csz[i] = 1;
	}
	int K;
	cin >> K;
	for (int i = 1;i <= K;++i) {
		int len;
		cin >> len;
		cyc[i].resize(len);
		int c = 0;
		for (int &u : cyc[i]) {
			cin >> u;
			cid[u] = i;
			csz[u] = len;
			cpos[u] = c++;
			dp[u].resize(len, inf);
			DE(u, cpos[u], len);
		}
	}

	//priority_queue<t3, vector<t3>, greater<t3>> q;
	//queue<pair<ll,int>> q;

	vector<vector<int>> q;
	auto putin = [&](int d, int x) {
		if (q.size() < d + 1) q.resize(d + 1);
		q[d].pb(x);
	};

	auto upd = [&](int x, ll d) {
		if (chmin(dp[x][d % csz[x]], d)) 
			putin(d, x);
	};

	upd(1, 0);


	// shortest path

	// now there are no two cycle being connected
	// check if at x, time is d can move to 
	auto valid = [&](int x, ll d, int u) {
		if (cid[u] == 0) return true;
		if (d % csz[u] == cpos[u]) return false;
		if (cid[x] == 0) return true;
		assert(cid[x] == cid[u]);
		if (cpos[u] == (cpos[x] - 1 + csz[x]) % csz[u]) {
			if (d % csz[u] == cpos[x]) return false;
		}
		return true;
	};

	for (int d = 0;d < q.size();++d) {
		for (int i = 0;i < q[d].size();++i) {
			int x = q[d][i];
//
//	while (q.size()) {
//		//auto [d, x] = q.front(); q.pop();
//		auto [d, x] = q.top(); q.pop();
		//if (d != dp[x][ d % csz[x] ]) continue;
			if (cid[x]) {
				for (int u : edge[x]) {
					if (cid[u] == 0) {
						upd(u, d + 1);
						continue;
					}
					else {
						if (valid(x, d + 1, u))
							upd(u, d + 1);
					}
				}
				if (valid(x, d + 1, x))
					upd(x, d + 1);
			}
			else {
				int mxc = hol;
				for (int u : edge[x]) {
					if (cid[u] == 0) {
						upd(u, d + 1);
						continue;
					}
					else {
						if (valid(x, d + 1, u))
							upd(u, d + 1);

						ll t = d + 1, m = t % csz[u];
						if (m != cpos[u]) {
							ll f = cpos[u] - m;
							if (f < 0) f += csz[u];
							t += f;
						}
						++t;
						if (valid(x, t, u))
							upd(u, t);
					}
				}
			}
		}
		vector<int>().swap(q[d]);
	}
	// 

	ll res = inf;
	for (auto v : dp[n]) chmin(res, v);
	
	if (res == inf) cout << "impossible\n";
	else cout << res << '\n';
}

Compilation message (stderr)

watchmen.cpp: In function 'int32_t main()':
watchmen.cpp:14:17: warning: statement has no effect [-Wunused-value]
   14 | #define DE(...) 0
      |                 ^
watchmen.cpp:52:4: note: in expansion of macro 'DE'
   52 |    DE(u, cpos[u], len);
      |    ^~
watchmen.cpp: In lambda function:
watchmen.cpp:61:16: warning: comparison of integer expressions of different signedness: 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   61 |   if (q.size() < d + 1) q.resize(d + 1);
      |       ~~~~~~~~~^~~~~~~
watchmen.cpp: In function 'int32_t main()':
watchmen.cpp:88:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |  for (int d = 0;d < q.size();++d) {
      |                 ~~^~~~~~~~~~
watchmen.cpp:89:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |   for (int i = 0;i < q[d].size();++i) {
      |                  ~~^~~~~~~~~~~~~
watchmen.cpp:111:9: warning: unused variable 'mxc' [-Wunused-variable]
  111 |     int mxc = hol;
      |         ^~~

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