Submission #945385

#	Time	Username	Problem	Language	Result	Execution time	Memory
945385		Xiaoyang	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	297 ms	25680 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
typedef long long ll;
 
#define fi first 
#define se second 
#define pll pair<ll,ll>
#define pb push_back
#define debug(x) cerr<<#x<<"="<<x<<endl;
#define MP make_pair
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define SZ(x) (ll)x.size()
#define ALL(x) x.begin(),x.end()
#define endl "\n"
const ll inf=1e18;
ll lowbit(ll x){return x&(-x);}


const ll maxn=1e5+5;
vector<pll>alist[maxn];
ll ds[maxn],dt[maxn],du[maxn],dv[maxn];

void dijkstra(ll st,ll dist[]){
	rep(i,0,maxn)dist[i]=inf;
	priority_queue<pll,vector<pll>,greater<pll>>s;
	s.push(MP(0ll,st));
	dist[st]=0;
	
	while(!s.empty()){
		auto u=s.top();
		s.pop();
		if(u.fi!=dist[u.se])continue;
		for(auto x:alist[u.se]){
			if(x.fi+u.fi<dist[x.se]){
				dist[x.se]=x.fi+u.fi;
				s.push(MP(dist[x.se],x.se));
			}
		}
	}
	
}

ll f[maxn],ff[maxn];
ll n,m;
ll t; 

void dijk(ll orig[],ll dist[]){
	priority_queue<pll,vector<pll>,greater<pll>>s;
	rep(i,1,n+1){
		dist[i]=orig[i];
		s.push(MP(orig[i],i));
	}
	while(!s.empty()){
		auto u=s.top();
		s.pop();
		if(u.fi!=dist[u.se])continue;
		for(auto x:alist[u.se]){
			//the edge is on the path from s to t => free
			if(ds[x.se]+x.fi+dt[u.se]==ds[t] and dist[u.se]<dist[x.se]){
				dist[x.se]=dist[u.se];
				s.push(MP(dist[x.se],x.se));
			}
		}
	}
}

ll s;
ll u,v;

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin>>n>>m;
	cin>>s>>t;
	cin>>u>>v;
	rep(i,0,m){
		ll a,b,c;cin>>a>>b>>c;
		alist[a].pb(MP(c,b));
		alist[b].pb(MP(c,a));
	}
	
	dijkstra(s,ds);
	dijkstra(t,dt);
	dijkstra(u,du);
	dijkstra(v,dv);
	
	dijk(dv,f);
	dijk(du,ff);
	ll ans=inf;
	
	rep(i,1,n+1){
		ans=min(ans,du[i]+f[i]);	
		ans=min(ans,dv[i]+ff[i]);
	}
	cout<<ans<<endl;
	return 0;
}

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