Submission #1179537

#	Time	Username	Problem	Language	Result	Execution time	Memory
1179537		MongHwa	Commuter Pass (JOI18_commuter_pass)	C++20	15 / 100	200 ms	22392 KiB

commuter_pass

#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#include <iostream>
#include <vector>
#include <queue>
#include <tuple>
using namespace std;

#define ll long long
#define INF 1e17
#define X first
#define Y second

vector<pair<int, int>> stage[100005];
vector<ll> sdist, udist, vdist;
bool status[100005];
int in[100005];
ll udp[100005], vdp[100005];
vector<int> graph[100005];
queue<int> q;
priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;

void dijkstra(vector<ll>& dist, int s)
{
    fill(dist.begin(), dist.end(), INF);
    dist[s] = 0;
    pq.push({0, s});
    while(!pq.empty())
    {
        ll d; int cur;
        tie(d, cur) = pq.top(); pq.pop();

        if(dist[cur] != d)
            continue;
        
        for(auto& nxt : stage[cur])
            if(dist[nxt.X] > d + nxt.Y)
            {
                dist[nxt.X] = d + nxt.Y;
                pq.push({dist[nxt.X], nxt.X});
            }
    }
}

void dfs(int cur)
{
    udp[cur] = udist[cur];
    vdp[cur] = vdist[cur];

    for(auto& nxt : stage[cur])
        if(sdist[nxt.X] + nxt.Y == sdist[cur] && !status[nxt.X])
        {
            status[nxt.X] = 1;
            graph[cur].push_back(nxt.X);
            in[nxt.X]++;
            dfs(nxt.X);
        }
}

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

    int n, m, s, t, u, v;
    cin >> n >> m >> s >> t >> u >> v;

    while(m--)
    {
        int a, b, c;
        cin >> a >> b >> c;

        stage[a].push_back({b, c});
        stage[b].push_back({a, c});
    }

    sdist.resize(n+1); udist.resize(n+1); vdist.resize(n+1);
    dijkstra(sdist, s);
    dijkstra(udist, u);
    dijkstra(vdist, v);

    dfs(t);

    ll ans = udist[v];
    q.push(t);
    while(!q.empty())
    {
        int cur = q.front(); q.pop();
        ans = min(ans, udp[cur] + vdp[cur]);

        for(int& nxt : graph[cur])
        {
            udp[nxt] = min(udp[nxt], udp[cur]);
            vdp[nxt] = min(vdp[nxt], vdp[cur]);

            in[nxt]--;
            if(in[nxt] == 0)
                q.push(nxt);
        }
    }

    cout << ans << '\n';
}

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