Submission #156501

#	Time	Username	Problem	Language	Result	Execution time	Memory
156501		staniewzki	Commuter Pass (JOI18_commuter_pass)	C++14	31 / 100	487 ms	22224 KiB

commuter_pass

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

ostream& operator<<(ostream &out, string str) {
	for(char c : str) out << c;
	return out;
}
 
template<class L, class R> ostream& operator<<(ostream &out, pair<L, R> p) {
	return out << "(" << p.first << ", " << p.second << ")";
}
 
template<class T> auto operator<<(ostream &out, T a) -> decltype(a.begin(), out) {
	out << "{";
	for(auto it = a.begin(); it != a.end(); it = next(it))
		out << (it != a.begin() ? ", " : "") << *it;
	return out << "}";
}
 
void dump() { cerr << "\n"; }
template<class T, class... Ts> void dump(T a, Ts... x) {
	cerr << a << ", ";
	dump(x...);
}
 
#ifdef DEBUG
#  define debug(...) cerr << "[" #__VA_ARGS__ "]: ", dump(__VA_ARGS__)
#else
#  define debug(...) false
#endif
 
#define REP(i, n) for(int i = 0; i < n; i++)
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define ST first
#define ND second
 
template<class T> int size(T && a) { return a.size(); }

using LL = long long;
using PII = pair<int, int>;

vector<vector<PII>> graph;
vector<LL> get_dist(int n, int s) {
	vector<LL> dist(n, 1e18);
	priority_queue<pair<LL, int>> Q;
	auto push = [&](int v, LL d) { 
		dist[v] = d;
		Q.emplace(-dist[v], v);
	};
	push(s, 0);

	while(!Q.empty()) {
		int v = Q.top().ND;
		Q.pop();
		for(PII e : graph[v]) {
			if(dist[e.ST] > dist[v] + e.ND)
				push(e.ST, dist[v] + e.ND);
		}
	}
	return dist;
}

vector<LL> dist_u, dist_v, dist_s, dist_t;
vector<bool> vis;

LL dfs(int v, vector<LL> &d, LL min_u, LL min_v) {
	vis[v] = true;
	min_u = min(min_u, dist_u[v]);
	min_v = min(min_v, dist_v[v]);
	LL ret = min_u + min_v;
	for(PII e : graph[v])
		if(d[v] == d[e.ST] + e.ND and not vis[e.ST])
			ret = min(ret, dfs(e.ST, d, min_u, min_v));
	debug(v, d, min_u, min_v);
	return ret;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int n, m;
	cin >> n >> m;
	
	int s, t, u, v;
	cin >> s >> t >> u >> v;
	s--, t--, u--, v--;
	graph.resize(n);
	REP(i, m) {
		int a, b, c;
		cin >> a >> b >> c;
		graph[a - 1].emplace_back(b - 1, c);
		graph[b - 1].emplace_back(a - 1, c);
	}

	dist_u = get_dist(n, u);
	dist_v = get_dist(n, v);
	dist_s = get_dist(n, s);
	dist_t = get_dist(n, t);

	debug(dist_s, dist_t);

	LL ans = dist_v[u];
	vis.resize(n);
	REP(i, 2) {
		LL min_u = 1e18, min_v = 1e18;
		int x = (i ? s : t);
		auto &d = (i ? dist_t : dist_s);
		fill(vis.begin(), vis.end(), false);
		ans = min(ans, dfs(x, d, min_u, min_v));
	}

	cout << ans << "\n";
}

Compilation message (stderr)

commuter_pass.cpp: In function 'LL dfs(int, std::vector<long long int>&, LL, LL)':
commuter_pass.cpp:74:27: warning: statement has no effect [-Wunused-value]
  debug(v, d, min_u, min_v);
                           ^
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:101:23: warning: statement has no effect [-Wunused-value]
  debug(dist_s, dist_t);
                       ^

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45