Submission #941805

#	Time	Username	Problem	Language	Result	Execution time	Memory
941805		carriewang	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	241 ms	45296 KiB

commuter_pass

#include <bits/stdc++.h>
#define ll long long
#define vi vector<int>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define sz(x) x.size()
#define all(x) x.begin(),x.end()
#define F first
#define S second
using namespace std;
const int maxn=1000005;
ll n,m,s,t,u,v,a,b,c;
vector<pll> g[maxn];
vector<ll> dist(int x){
    vector<ll> ret(n,1e18);
    priority_queue<pll,vector<pll>,greater<pll>> pq;
    pq.emplace(0,x);
    ret[x]=0;
    while(!pq.empty()){
        auto [p,q]=pq.top();
        pq.pop();
        if(p>ret[q]) continue;
        for(auto [y,z]:g[q]){
            if(p+z<ret[y]){
                pq.emplace(p+z,y);
                ret[y]=p+z;
            }
        }
    }
    return ret;
}
int main(){
    ios::sync_with_stdio(0),cin.tie(0);
    cin >> n >> m;
    cin >> s >> t >> u >> v;
    s--,t--,u--,v--;
    for(int i=0;i<m;i++){
        cin >> a >> b >> c;
        a--,b--;
        g[a].emplace_back(b,c);
        g[b].emplace_back(a,c);
    }
    auto ds=dist(s),dt=dist(t),du=dist(u),dv=dist(v);
    vector<pll> ask;
    for(int i=0;i<n;i++){
        if(ds[i]+dt[i]==ds[t]) ask.emplace_back(dt[i],i);
    }
    sort(all(ask));
    ll ans=du[v];
    vector<ll> um(n,1e18),vm(n,1e18);
    for(auto [_,x]:ask){
        um[x]=du[x],vm[x]=dv[x];
        for(auto [p,q]:g[x]){
            if(dt[p]+q==dt[x]){
                um[x]=min(um[x],um[p]);
                vm[x]=min(vm[x],vm[p]);
            }
            ans=min(ans,min(um[x]+dv[x],vm[x]+du[x]));
        }
    }
    cout << ans << "\n";
}

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