Submission #376516

#	Time	Username	Problem	Language	Result	Execution time	Memory
376516		astoria	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	527 ms	25784 KiB

commuter_pass

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

#define int long long
const int N=100005;
int n,m;
int dist[4][N]; //0=s,1=t,2=u,3=v
vector<pair<int,int> > adj[N];
int mnu[2][N];

void dijk(int src, int pp){
	priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > pq;
	memset(dist[pp],-1,sizeof(dist[pp]));
	dist[pp][src] = 0;
	pq.push({0,src});
	while(!pq.empty()){
		int v=pq.top().second, d=pq.top().first; pq.pop();
		if(dist[pp][v] != d) continue;
		for(auto ii : adj[v]){
			int nv=ii.first, nd=ii.second+d;
			if(dist[pp][nv]==-1 || nd<dist[pp][nv]){
				dist[pp][nv] = nd; pq.push({nd,nv});
			}
		}
	}
}

void special_dijk(int src, int pp){
	int dis[N]; memset(dis,-1,sizeof(dis));
	priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > pq;
	pq.push({0,src}); dis[src]=0;
	while(!pq.empty()){
		int v=pq.top().second, d=pq.top().first; pq.pop();
		if(dis[v]!=d) continue;
		if(mnu[pp][v]==-1) mnu[pp][v] = dist[2][v];
		else mnu[pp][v] = min(mnu[pp][v], dist[2][v]);
		for(auto ii : adj[v]){
			int nv=ii.first, nd=ii.second+d;
			if(dis[nv]==-1 || nd<dis[nv]){
				dis[nv]=nd; pq.push({nd,nv}); mnu[pp][nv] = mnu[pp][v];
			}
			else if(nd==dis[nv]){
				if(mnu[pp][nv]==-1) mnu[pp][nv] = mnu[pp][v];
				else mnu[pp][nv] = min(mnu[pp][nv],mnu[pp][v]);
			}
		}
	}
}

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);
	int s,t,u,v;
	cin>>n>>m>>s>>t>>u>>v;
	memset(mnu,-1,sizeof(mnu));
	for(int i=0; i<m; i++){
		int a,b,c;
		cin>>a>>b>>c;
		adj[a].push_back({b,c});
		adj[b].push_back({a,c});
	}
	dijk(s,0); dijk(t,1); dijk(u,2); dijk(v,3);
	
	special_dijk(s,0); special_dijk(t,1);
	
	int an=dist[2][v];
	for(int i=1; i<=n; i++){
		if(dist[0][i] + dist[1][i] != dist[0][t]) continue; //not on shortest path
		int val = min(mnu[0][i],mnu[1][i])+dist[3][i];
		//if(val==0) cout<<i<<endl;
		an=min(an,val);
	}
	cout<<an<<endl;
	
	/*for(int i=1; i<=n; i++){
		cout<<mnu[0][i]<<' '<<mnu[1][i]<<' '<<dist[3][i]<<'\n';
	}*/
	//cout<<dist[0][4]<<' '<<dist[1][4]<<endl;
}

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