Submission #1332012

#TimeUsernameProblemLanguageResultExecution timeMemory
1332012tkm_algorithmsCommuter Pass (JOI18_commuter_pass)C++20
100 / 100
331 ms23920 KiB
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
#define int ll
using P = pair<int, int>;
#define all(x) x.begin(), x.end()
#define rep(x,s,e) for (auto x=(s)-((s)>(e));x!=(e)-((s)>(e));((s)<(e)?x++:x--))
#define sz(x) (int)x.size()
const char nl = '\n';
const int inf = 1e5*1e9;
const int NMAX = 1e5+10;
vector<P> g[NMAX];
int in[NMAX];

void djk(int src, vector<int> &d) {
	for (auto &i: d)i = inf; d[src] = 0;
	priority_queue<P, vector<P>, greater<P>> pq;
	pq.push(P(0, src));
	
	while (!pq.empty()) {
		auto [dist, nd] = pq.top(); pq.pop();
		if (d[nd] != dist)continue;
		for (auto [ch, w]: g[nd])
			if (dist+w < d[ch])
				d[ch] = dist+w,
				pq.push({d[ch], ch});
	}
}

void solve() {
	int n, m; cin >> n >> m;
	int s, t; cin >> s >> t;
	int u, v; cin >> u >> v;
	
	while (m--) {
		int x, y, z; cin >> x >> y >> z;
		g[x].push_back(P(y, z));
		g[y].push_back(P(x, z));
	}
	
	vector<int> ds(n+1), dt(n+1), du(n+1), dv(n+1);
	djk(s, ds), djk(t, dt);
	djk(u, du), djk(v, dv);
	
	vector<int> g2[n+1];
	rep(i, 1, n+1) {
		for (auto [j, w]: g[i])
			if (ds[i]+dt[j]+w == ds[t])
				g2[i].push_back(j),
				in[j] += 1;
	}
	
	vector<int> dp1(n+1, inf), dp2(n+1, inf);
	int res = du[v];
	queue<int> q; q.push(s);
	while (!q.empty()) {
		int nd = q.front(); q.pop();
		dp1[nd] = min(dp1[nd], du[nd]);
		dp2[nd] = min(dp2[nd], dv[nd]);
		for (auto i: g2[nd]) {
			dp1[i] = min(dp1[i], dp1[nd]);
			dp2[i] = min(dp2[i], dp2[nd]);
			in[i] -= 1;
			if (in[i] == 0)q.push(i);
		}
		
		res = min(res, min(dp1[nd]+dv[nd], dp2[nd]+du[nd]));
	}
	
	cout << res << nl;
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    solve();
    return 0;
}

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