Submission #1031759

#	Time	Username	Problem	Language	Result	Execution time	Memory
1031759		Nonoze	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	529 ms	87708 KiB

commuter_pass

/*
*	Author: Nonoze
*	Created: Tuesday 23/07/2024
*/
#include <bits/stdc++.h>
using namespace std;

#ifndef _IN_LOCAL
	#define dbg(...)
#endif

#define endl '\n'
#define endlfl '\n' << flush
#define quit(x) return (void)(cout << x << endl)

template<typename T> void read(T& x, bool write=0, bool write2=1) { if (write && write2) cout << x << endl; else if (write) cout << x << ' '; else cin >> x;}
template<typename T1, typename T2> void read(pair<T1, T2>& p, bool write=0, bool write2=1) { read(p.first, write, 0), read(p.second, write, 0); if (write && write2) cout << endl;}
template<typename T> void read(vector<T>& v, bool write=0) { for (auto& x : v) read(x, write, 0); if (write) cout << endl; }
template<typename T1, typename T2> void read(T1& x, T2& y, bool write=0) { read(x, write), read(y, write); if (write) cout << endl; }
template<typename T1, typename T2, typename T3> void read(T1& x, T2& y, T3& z, bool write=0) { read(x, write), read(y, write), read(z, write); if (write) cout << endl; }
template<typename T1, typename T2, typename T3, typename T4> void read(T1& x, T2& y, T3& z, T4& zz, bool write=0) { read(x, write), read(y, write), read(z, write), read(zz, write); if (write) cout << endl; }
template<typename T> void print(T x) { read(x, 1); }
template<typename T1, typename T2> void print(T1 x, T2 y) { read(x, y, 1); }
template<typename T1, typename T2, typename T3> void print(T1 x, T2 y, T3 z) { read(x, y, z, 1); }
template<typename T1, typename T2, typename T3, typename T4> void print(T1 x, T2 y, T3 z, T4 zz) { read(x, y, z, zz, 1); }

#define sz(x) (int)(x.size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define cmin(a, b) a = min(a, b)
#define cmax(a, b) a = max(a, b)

#define int long long
const int inf = numeric_limits<int>::max() / 4;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MOD = 1e9+7, LOG=25;



void solve();

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int tt=1;
	// cin >> tt;
	while(tt--) solve();
	return 0;
}




int n, m;
vector<vector<pair<int, int>>> adj, prec, nxt;
vector<bool> used;

void dfs(int u) {
	used[u]=1;
	for (auto [v, w]: prec[u]) if (!used[v]) dfs(v);
}

void dijkstra(int s, int t) {
	vector<int> dist(n, inf);
	vector<bool> visited(n);
	priority_queue<pair<int, int>, vector<pair<int, int>>, greater<>> pq;
	pq.push({0, s});
	dist[s]=0;
	while (!pq.empty()) {
		auto [d, u]=pq.top(); pq.pop();
		if (visited[u]) continue;
		visited[u]=1;
		for (auto [v, w]: adj[u]) {
			if (dist[v]>dist[u]+w) {
				dist[v]=dist[u]+w;
				prec[v].clear();
				prec[v].pb({u, w});
				pq.push({dist[v], v});
			} else if (dist[v]==dist[u]+w) {
				prec[v].pb({u, w});
			}
		}
	}
	dfs(t);
}


void solve() {
	read(n, m);
	int s, t, s2, t2; read(s, t, s2, t2); s--, t--, s2--, t2--;
	adj.resize(n);
	for (int i=0; i<m; i++) {
		int a, b, c; read(a, b, c); a--, b--;
		adj[a].pb({b, c});
		adj[b].pb({a, c});
	}
	prec.resize(n), nxt.resize(n), used.resize(n);
	dijkstra(t, s); swap(prec, nxt); dijkstra(s, t);
	// dbg(prec);
	// dbg(nxt);
	// dbg(used);
	s=s2, t=t2;
	vector<vector<vector<int>>> dist(n, vector<vector<int>>(3, vector<int>(3, inf)));
	vector<vector<vector<bool>>> visited(n, vector<vector<bool>>(3, vector<bool>(3)));
	priority_queue<vector<int>, vector<vector<int>>, greater<> > pq;
	pq.push({0, s, 0, 0});
	dist[s][0][0]=0;
	while (!pq.empty()) {
		auto vec=pq.top(); pq.pop(); int d=vec[0], u=vec[1], already=vec[2], dir=vec[3];
		if (visited[u][already][dir]) continue;
		visited[u][already][dir]=1;
		if (u==t) {
			cout << d << endl;
			return;
		}
		if (used[u] && already!=2) {
			if (dir!=1) {
				for (auto [v, w]: prec[u]) {
					if (d<dist[v][1][2]) dist[v][1][2]=d, pq.push({d, v, 1, 2});
				}
			}
			if (dir!=2) {
				for (auto [v, w]: nxt[u]) {
					if (d<dist[v][1][1]) dist[v][1][1]=d, pq.push({d, v, 1, 1});
				}
			}
		}
		if (already==1) already=2, dir=0;
		for (auto [v, w]: adj[u]) {
			if (dist[v][already][dir]>d+w) {
				dist[v][already][dir]=d+w;
				pq.push({d+w, v, already, dir});
			}
		}
	}
}

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