Submission #787819

#	Time	Username	Problem	Language	Result	Execution time	Memory
787819		guagua0407	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	287 ms	25400 KiB

commuter_pass

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

const int mxn=1e5+5;
vector<pair<int,ll>> adj[mxn];
int n,m;
int S,T,U,V;
vector<int> vec;

vector<ll> dij(int node){
    priority_queue<pair<ll,ll>,vector<pair<ll,ll>>,greater<pair<ll,ll>>> pq;
    vector<ll> d(n,(ll)1e18);
    d[node]=0;
    pq.push({0,node});
    while(!pq.empty()){
        auto v=pq.top();
        pq.pop();
        if(v.f!=d[v.s]) continue;
        for(auto u:adj[v.s]){
            if(d[v.s]+u.s<d[u.f]){
                d[u.f]=d[v.s]+u.s;
                pq.push({d[u.f],u.f});
            }
        }
    }
    return d;
}

vector<vector<ll>> d;

bool comp(int a,int b){
    return d[S][a]<d[S][b];
}

int main() {_
    cin>>n>>m;
    cin>>S>>T>>U>>V;
    S--;
    T--;
    U--;
    V--;
    for(int i=0;i<m;i++){
        int a,b,c;
        cin>>a>>b>>c;
        a--;
        b--;
        adj[a].push_back({b,c});
        adj[b].push_back({a,c});
    }
    d.resize(n);
    for(int i=0;i<n;i++){
        if(i!=S and i!=T and i!=U and i!=V) continue;
        d[i]=dij(i);
    }
    ll ans=(ll)1e18;
    vector<int> vec;
    for(int i=0;i<n;i++){
        if(d[S][i]+d[T][i]==d[S][T]) vec.push_back(i);
    }
    sort(all(vec),comp);
    vector<ll> mn(n,(ll)1e18);
    for(auto v:vec){
        mn[v]=d[U][v];
        for(auto u:adj[v]){
            if(d[S][u.f]+u.s==d[S][v]) mn[v]=min(mn[v],mn[u.f]);
        }
        //cout<<v+1<<' '<<mn[v]<<'\n';
        ans=min(ans,mn[v]+d[V][v]);
    }
    mn=vector<ll>(n,(ll)1e18);
    for(auto v:vec){
        mn[v]=d[V][v];
        for(auto u:adj[v]){
            if(d[S][u.f]+u.s==d[S][v]) mn[v]=min(mn[v],mn[u.f]);
        }
        //cout<<v+1<<' '<<mn[v]<<'\n';
        ans=min(ans,mn[v]+d[U][v]);
    }
    cout<<min(d[U][V],ans)<<'\n';
    return 0;
}
//maybe its multiset not set

Compilation message (stderr)

commuter_pass.cpp: In function 'void setIO(std::string)':
commuter_pass.cpp:12:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:13:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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