Submission #718696

#	Time	Username	Problem	Language	Result	Execution time	Memory
718696		sofija6	Commuter Pass (JOI18_commuter_pass)	C++14	39 / 100	2093 ms	43880 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

ll INF=LONG_LONG_MAX;
ll m, n, s, t, u, v;
vector<pair<ll, ll> >graff[200010];
vector<ll>dag[200010];
bool check1[200010], check2[200010];
ll distu[200010], distv[200010], dists[200010], distt[200010];
ll res=INF;
set<pair<ll,ll> > grane;
void dijkstra(ll cvor, ll *dist)
{
    for(int i=0; i<100010; i++)
    {
        check1[i]=false;
        dist[i]=INF;
    }
    priority_queue<pair<ll, ll> >ord;
    dist[cvor]=0;
    ord.push({0, cvor});
    while(!ord.empty())
    {
        int cv=ord.top().second;
        ord.pop();
        if(check1[cv])continue;
        check1[cv]=true;
        for(int j=0; j<graff[cv].size(); j++)
        {
            ll pp=graff[cv][j].first;
            dist[pp]=min(dist[pp], dist[cv]+graff[cv][j].second);
            if(!check1[pp])ord.push({-dist[pp], pp});
        }
    }
}

void dfs1(ll prosli, ll cvor)
{
    if(dists[cvor]+distt[cvor]!=dists[t])return;
    if(dists[cvor]-dists[prosli]<0)return;
    dag[prosli].push_back(cvor);
    if(cvor==t)return;
    for(int i=0; i<graff[cvor].size(); i++)
    {
        if (dists[cvor]+graff[cvor][i].second+distt[graff[cvor][i].first]==dists[t] && !grane.count({cvor, graff[cvor][i].first}))
        {
            grane.insert({cvor, graff[cvor][i].first});
            dfs1(cvor, graff[cvor][i].first);
        }
    }
    return;
}

void dfs2(ll cvor, ll minv, ll minu)
{
    minv=min(minv, distv[cvor]);
    minu=min(minu, distu[cvor]);
    res=min(res, minv+minu);
    if(cvor==t)return;
    for(int i=0; i<dag[cvor].size(); i++)
    {
        if (!grane.count({cvor,dag[cvor][i]}) || minv>distv[dag[cvor][i]] || minu>distu[dag[cvor][i]])
        {
            grane.insert({cvor,dag[cvor][i]});
            dfs2(dag[cvor][i], minv, minu);
        }
    }
    return;
}

void solve()
{
    priority_queue<pair<ll,ll> > q;
    ll U[100010],V[100010];
    for (ll i=1;i<=n;i++)
    {
        U[i]=INF;
        V[i]=INF;
    }
    U[s]=distu[s];
    V[s]=distv[s];
    q.push({-U[s],s});
    while (!q.empty())
    {
        ll t=q.top().second,d=abs(q.top().first);
        q.pop();
        if (U[t]!=d)
            continue;
        res=min(res,U[t]+V[t]);
        for (auto next : dag[t])
        {
            ll i=next;
            if (U[i]==INF)
            {
                U[i]=distu[i];
                V[i]=distv[i];
                q.push({-U[i],i});
            }
            if (U[t]<U[i])
            {
                U[i]=U[t];
                V[i]=min(distv[i],V[t]);
                q.push({-U[i],i});
            }
            else if (U[t]==U[i])
            {
                if (distv[i]<=V[t])
                    V[i]=distv[i];
                else
                {
                    V[i]=V[t];
                    q.push({-U[i],i});
                }
            }
        }
    }
    for (ll i=1;i<=n;i++)
    {
        U[i]=INF;
        V[i]=INF;
    }
    U[s]=distu[s];
    V[s]=distv[s];
    q.push({-V[s],s});
    while (!q.empty())
    {
        ll t=q.top().second,d=abs(q.top().first);
        q.pop();
        if (V[t]!=d)
            continue;
        res=min(res,U[t]+V[t]);
        for (auto next : dag[t])
        {
            ll i=next;
            if (V[i]==INF)
            {
                V[i]=distv[i];
                U[i]=distu[i];
                q.push({-V[i],i});
            }
            if (V[t]<V[i])
            {
                V[i]=V[t];
                U[i]=min(distu[i],U[t]);
                q.push({-V[i],i});
            }
            else if (V[t]==V[i])
            {
                if (distu[i]<=U[t])
                    U[i]=distu[i];
                else
                {
                    U[i]=U[t];
                    q.push({-V[i],i});
                }
            }
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie();
    cout.tie();
    cin>>n>>m;
    cin>>s>>t;
    cin>>u>>v;
    ll a, b, c;
    for(int i=0; i<m; i++)
    {
        cin>>a>>b>>c;
        graff[a].push_back({b, c});
        graff[b].push_back({a, c});
    }
    dijkstra(u, distu);
    dijkstra(v, distv);
    dijkstra(s, dists);
    dijkstra(t, distt);
    dists[0]=0;
    dfs1(0, s);
    ///dfs2(s, INF, INF);
    solve();
    cout<<min(res, distv[u]);
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void dijkstra(ll, ll*)':
commuter_pass.cpp:30:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |         for(int j=0; j<graff[cv].size(); j++)
      |                      ~^~~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'void dfs1(ll, ll)':
commuter_pass.cpp:45:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |     for(int i=0; i<graff[cvor].size(); i++)
      |                  ~^~~~~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'void dfs2(ll, ll, ll)':
commuter_pass.cpp:62:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for(int i=0; i<dag[cvor].size(); i++)
      |                  ~^~~~~~~~~~~~~~~~~

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