Submission #681780

#	Time	Username	Problem	Language	Result	Execution time	Memory
681780		zeroesandones	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	424 ms	31548 KiB

commuter_pass

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

typedef long long ll;
typedef long double ld;
typedef vector<ll> vi;
typedef pair<ll, ll> pi;

#define FOR(i, j, k) for (ll i = j; i < (ll) k; ++i)
#define FORD(i, j, k) for (ll i = j; i >= (ll) k; --i)
#define nl "\n"
#define sp " "

#define all(x) (x).begin(), (x).end()
#define sc second
#define fr first
#define pb emplace_back

struct edge {
    ll b, w;
};

const ll mxN = 1e5 + 5;
ll n, m;
vector<edge> adj[mxN];
vi distU, distV;

vi djik(ll x) {
    vi dist(n + 1, 1e15);
    bool vis[n + 1] = {};
    priority_queue<pi> pq;
    dist[x] = 0;
    pq.emplace(0, x);
    while(!pq.empty()) {
        ll u = pq.top().sc;
        pq.pop();
        if(vis[u]) continue;
        vis[u] = true;

        for(auto [v, w] : adj[u]) {
            if(dist[v] > dist[u] + w) {
                dist[v] = dist[u] + w;
                pq.emplace(-dist[v], v);
            }
        }
    }

    return dist;
}

ll solve(ll start, ll end) {
    ll dp[2][100001];
    bool visited[100001];
    ll ds[100001];
    fill(dp[0], dp[0] + 100001, LLONG_MAX / 2);
	fill(dp[1], dp[1] + 100001, LLONG_MAX / 2);
	fill(ds, ds + 100001, LLONG_MAX / 2);
	fill(visited, visited + 100001, false);
	priority_queue<pair<ll, pair<ll, ll>>> pq;
	pq.push({0, {start, 0}});
	dp[0][0] = dp[1][0] = LLONG_MAX/ 2;
	while (!pq.empty()) {
		ll c, node, par;
		pair<ll, ll> p;
		tie(c, p) = pq.top();
		tie(node, par) = p;
		pq.pop();
		if (!visited[node]) {
			visited[node] = true;
			ds[node] = -c;
			dp[0][node] = min(distU[node], dp[0][par]);
			dp[1][node] = min(distV[node], dp[1][par]);
			for (auto i : adj[node]) pq.push({c - i.w, {i.b, node}});
		} else if (-c == ds[node]) {
			if (min(distU[node], dp[0][par]) + min(distV[node], dp[1][par]) <= dp[0][node] + dp[1][node]) {
				dp[0][node] = min(distU[node], dp[0][par]);
				dp[1][node] = min(distV[node], dp[1][par]);
			}
		}
	}
	return dp[0][end] + dp[1][end];
}

void solve()
{
    cin >> n >> m;

    ll s, t;
    cin >> s >> t;

    ll u, v;
    cin >> u >> v;

    FOR(i, 0, m) {
        ll a, b, c;
        cin >> a >> b >> c;
        edge curr;
        curr.b = b;
        curr.w = c;
        adj[a].pb(curr);
        curr.b = a;
        adj[b].pb(curr);
    }

    distU = djik(u);
    distV = djik(v);

    ll ans = distU[v];

    ll v1 = solve(s, t);
    ll v2 = solve(t, s);
    ans = min({ans, v1, v2});
    cout << ans << nl;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    ll t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
}

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