Submission #1241524

#	Time	Username	Problem	Language	Result	Execution time	Memory
1241524		tminh	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	188 ms	41804 KiB

commuter_pass

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

#define task ""
#define ll long long
#define endl '\n'
#define fi first
#define se second
#define vall(a) (a).begin(), (a).end()
#define sze(a) (int)a.size()
#define pii pair<int, int>
#define pll pair<ll, ll>


#define ep emplace_back
#define pb push_back
#define pf push_front


const ll mod = 1e9 + 7;
const int N = 1e6 + 5;
const ll oo = 1e18;

bool START;

int n, m, S, T, U, V;
ll dist[N][2], d[N], dp[N][2];
vector<pll> adj[N];


void dijkstra(int s, bool t) {
	priority_queue<pll, vector<pll>, greater<pll>> q;
	for (int i = 1; i <= n; ++i) dist[i][t] = oo;
	dist[s][t] = 0;
	q.push(make_pair(dist[s][t], s));
	while(!q.empty()) {
		auto[c, u] = q.top();
		q.pop();
		
		if (c != dist[u][t]) continue;
		for (auto[v, w] : adj[u]) {
			if (dist[v][t] > dist[u][t] + w) {
				dist[v][t] = dist[u][t] + w;
				q.push(make_pair(dist[v][t], v));
			}
		}
	}
}

int par[N];
void dijk(int s) {
	priority_queue<pll, vector<pll>, greater<pll>> q;
	for (int i = 1; i <= n; ++i) {
		d[i] = dp[i][0] = dp[i][1] = oo;
		par[i] = 0;
	}
	d[s] = 0;	
	q.push(make_pair(d[s], s));
	
	dp[s][0] = dist[s][0];
	dp[s][1] = dist[s][1];
	while(!q.empty()) {
		auto[c, u] = q.top();
		q.pop();
		
		if (c != d[u]) continue;

		for (auto[v, w] : adj[u]) {
			if (d[v] > d[u] + w) {
				d[v] = d[u] + w;
				q.push(make_pair(d[v], v));
				par[v] = u;
				
				dp[v][0] = min(dp[par[v]][0], dist[v][0]);
				dp[v][1] = min(dp[par[v]][1], dist[v][1]);
			}
			else if (d[v] == d[u] + w) {
				if (min(dist[v][0], dp[u][0]) + min(dist[v][1], dp[u][1]) <= dp[v][0] + dp[v][1]) {
					dp[v][0] = min(dist[v][0], dp[u][0]);
					dp[v][1] = min(dist[v][1], dp[u][1]);
					par[v] = u;
				}
				 
			}
		}	
	}
}

inline void solve() {
	dijkstra(U, 0);
	dijkstra(V, 1);
	ll ans = dist[V][0];
	dijk(S);
	ans = min(ans, dp[T][0] + dp[T][1]);
	dijk(T);
	ans = min(ans, dp[S][0] + dp[S][1]);
	cout << ans;
}


inline void input() {
    cin >> n >> m >> S >> T >> U >> V;
    for (int i = 1; i <= m; ++i) {
    	int u, v, c;
    	cin >> u >> v >> c;
    	adj[u].pb(make_pair(v, c));
    	adj[v].pb(make_pair(u, c));
    }
    return solve();
}
bool END;

int main() {
    if(fopen(task ".inp", "r")) {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    input();
    
    
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << 's' << endl;
    cerr << "Memory: " << fabs ((&END - &START)) / 1048576.0 << "MB\n";
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:115:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  115 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:116:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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