Submission #884417

#	Time	Username	Problem	Language	Result	Execution time	Memory
884417		marvinthang	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	130 ms	3412 KiB

ho_t4

/*************************************
*    author: marvinthang             *
*    created: 07.12.2023 16:37:49    *
*************************************/

#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i-- > 0; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
    #include "debug.h"
#else
    #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
    #define DB(...) 23
    #define db(...) 23
    #define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

// end of template

const int INF = (int) 1e9 + 7;

struct Edge {
	int u, v, c, d;
	Edge(int u = 0, int v = 0, int c = 0, int d = 0): u(u), v(v), c(c), d(d) {}
};

void process(void) {
	int n, m; cin >> n >> m;
	vector <vector <int>> adj(n), radj(n);
	vector <Edge> edges;
	REP(i, m) {
		int u, v, c, d; cin >> u >> v >> c >> d;
		--u; --v;
		edges.emplace_back(u, v, c, d);
		adj[u].push_back(i);
		radj[v].push_back(i);
	}
	vector <int> dist1, distn;
	auto solve = [&] (int s, int t, vector <int> &res) {
		vector <int> dists, distt, trace(n);
		vector <bool> used(n);
		auto Dijkstra = [&] (int s, vector <int> &dist, const vector <vector <int>> &adj) {
			dist.assign(n, INF);
			fill(ALL(used), false);
			dist[s] = trace[s] = 0;
			REP(love, n - 1) {
				int u = -1;
				REP(i, n) if (!used[i] && (u == -1 || dist[i] < dist[u])) u = i;
				used[u] = true;
				for (int i: adj[u]) {
					int v = edges[i].u ^ edges[i].v ^ u;
					if (minimize(dist[v], dist[u] + edges[i].c)) trace[v] = i;
				}
			}
		};
		res.assign(m + 1, INF);
		Dijkstra(t, distt, radj);
		Dijkstra(s, dists, adj);
		res[m] = dists[t];
		vector <bool> in_path(m);
		if (res[m] < INF) {
			int u = t;
			while (u != s) {
				in_path[trace[u]] = true;
				u = edges[trace[u]].u;
			}
		}
		vector <int> distm;
		REP(i, m) {
			auto [u, v, c, d] = edges[i];
			if (!in_path[i]) {
				res[i] = min(res[m], dists[v] + distt[u] + c);
			} else {
				adj[u].erase(find(ALL(adj[u]), i));
				Dijkstra(s, distm, adj);
				res[i] = distm[t];
				adj[u].push_back(i);
			}
		}
	};
	solve(0, n - 1, dist1);
	solve(n - 1, 0, distn);
	int res = INF + INF;
	REP(i, m + 1) if (dist1[i] < INF && distn[i] < INF) minimize(res, dist1[i] + distn[i] + (i == m ? 0 : edges[i].d));
	cout << (res >= INF + INF ? -1 : res) << '\n';
}

int main(void) {
	ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
	file("JOI20_ho_t4");
	// int t; cin >> t; while (t--)
	process();
	// cerr << "Time elapsed: " << TIME << " s.\n";
	return (0^0);
}

Compilation message (stderr)

ho_t4.cpp: In function 'int main()':
ho_t4.cpp:30:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
ho_t4.cpp:117:2: note: in expansion of macro 'file'
  117 |  file("JOI20_ho_t4");
      |  ^~~~
ho_t4.cpp:30:94: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
ho_t4.cpp:117:2: note: in expansion of macro 'file'
  117 |  file("JOI20_ho_t4");
      |  ^~~~

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63