Submission #76566

#	Time	Username	Problem	Language	Result	Execution time	Memory
76566		Vasiljko	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	535 ms	23792 KiB

commuter_pass

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

typedef long long ll;
const ll MOD = 1e9+7;
const int N =1e5+5;
const ll INF = 1e18;

int n,m,T;
bool vis[N];
ll du[N],dv[N],ds[N],dt[N],d1[N],d2[N],dp[N],ans;
vector<pair<int,ll> >v[2*N];
priority_queue<pair<ll,int> >pq;
multiset<ll>su,sv;

void Dijkstra(ll *d,int s){
    for(int i=1;i<=N;i++)d[i]=INF;
    d[s]=0;
    pq.push({-d[s],s});

    while(!pq.empty()){
        auto cur=pq.top();
        pq.pop();

        for(auto e:v[cur.second]){
            if(d[cur.second]+e.second<d[e.first]){
                d[e.first]=d[cur.second]+e.second;
                pq.push({-d[e.first],e.first});
            }
        }
    }
}

void solve(ll *d,ll *dd)
{
    for(int i=1;i<=n;i++)dd[i]=d[i],pq.push({-dd[i],i});

	while(!pq.empty())
	{
		int r = pq.top().second;
		pq.pop();
		for(auto x:v[r])
		{
			int u = x.first;
			int c = x.second;
			if(ds[r]+c+dt[u]==ds[T]&&dd[u]>dd[r]){
                dd[u]=dd[r];
                pq.push({-dd[u],u});
			}
		}
	}
}

ll dfs(int s,int dir){
   /* vis[s]=true;

    for(auto e:v[s]){
        if(dir==0){//go from s to t
            if(ds[s]+e.second+dt[e.first]==ds[T]&&!vis[e.first]){
                dp[s]=min(dp[s],dfs(e.first,dir));
            }
        }else{
            if(dt[s]+e.second+ds[e.first]==ds[T]&&!vis[e.first]){
                dp[e.first]=min(dp[s],dfs(e.first,dir));
            }
        }
        ans=min(ans,dp[s]+dv[s]);
    }
    return dp[s];*/
    if(dp[s]==-1){
        dp[s]=dv[s];
        for(auto e : v[s])
            if(dir?ds[s]+e.second+dt[e.first]==ds[T]:dt[s]+e.second+ds[e.first]==ds[T])
                dp[s]=min(dfs(e.first,dir),dp[s]);
        ans=min(ans,du[s]+dp[s]);
    }
	return dp[s];

}

int main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int s,t,a,b,x,y,z;

    cin>>n>>m;
    cin>>s>>t;
    cin>>a>>b;

    T=t;

    for(int i=1;i<=m;i++){
        cin>>x>>y>>z;
        v[x].push_back({y,z});
        v[y].push_back({x,z});
    }

    Dijkstra(du,a);
    Dijkstra(dv,b);
    Dijkstra(ds,s);
    Dijkstra(dt,t);
    //solve(dv,d1);
    //solve(du,d2);
    ans=du[b];
    memset(dp,-1,sizeof(dp));
    dfs(s,1);
    memset(dp,-1,sizeof(dp));
    dfs(t,0);

    cout<<ans;
    return 0;
}

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