Submission #754362

#	Time	Username	Problem	Language	Result	Execution time	Memory
754362		jamielim	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	518 ms	19408 KiB

commuter_pass

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

#define fi first
#define se second
#define mp make_pair
#define pb emplace_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<ii,ii> i4;
typedef vector<int> vi;
const int MOD=1000000007;
const int INF=1012345678;
const ll LLINF=1012345678012345678LL;
const double PI=3.1415926536;
const double EPS=1e-14;

int n,m;
int s,t,u,v;
vector<ii> adj[100005];
ll dist[4][100005];
ll minsofar[2][100005];
priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;

void dijkstra(int idx,int source){
	for(int i=0;i<n;i++)dist[idx][i]=LLINF;
	dist[idx][source]=0;
	pq.push(mp(0,source));
	while(!pq.empty()){
		pair<ll,int> cur=pq.top();pq.pop();
		for(ii i:adj[cur.se]){
			if(dist[idx][i.fi]>dist[idx][cur.se]+i.se){
				dist[idx][i.fi]=dist[idx][cur.se]+i.se;
				pq.push(mp(dist[idx][i.fi],i.fi));
			}
		}
	}
}

int main(){
	scanf("%d%d%d%d%d%d",&n,&m,&s,&t,&u,&v);s--;t--;u--;v--;
	int a,b,c;
	for(int i=0;i<m;i++){
		scanf("%d%d%d",&a,&b,&c);a--;b--;
		adj[a].pb(b,c);
		adj[b].pb(a,c);
	}
	dijkstra(0,u);
	dijkstra(1,v);
	dijkstra(2,s);
	
	ll ans=LLINF;
	for(int i=0;i<n;i++){
		dist[3][i]=LLINF;
		minsofar[0][i]=dist[0][i];
		minsofar[1][i]=dist[1][i];
	}
	dist[3][t]=0;
	pq.push(mp(0,t));
	while(!pq.empty()){
		pair<ll,int> cur=pq.top();pq.pop();
		for(ii i:adj[cur.se]){
			if(dist[3][i.fi]>dist[3][cur.se]+i.se){
				dist[3][i.fi]=dist[3][cur.se]+i.se;
				for(int j=0;j<2;j++)minsofar[j][i.fi]=min(minsofar[j][cur.se],dist[j][i.fi]);
				pq.push(mp(dist[3][i.fi],i.fi));
			}else if(dist[3][i.fi]==dist[3][cur.se]+i.se){
				for(int j=0;j<2;j++)minsofar[j][i.fi]=min(minsofar[j][cur.se],minsofar[j][i.fi]);
			}
		}
	}
	for(int i=0;i<n;i++){
		if(dist[2][i]+dist[3][i]==dist[2][t]){
			ans=min(ans,minsofar[0][i]+dist[1][i]);
			ans=min(ans,minsofar[1][i]+dist[0][i]);
		}
	}
	
	printf("%lld",min(ans,dist[0][v]));
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:43:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |  scanf("%d%d%d%d%d%d",&n,&m,&s,&t,&u,&v);s--;t--;u--;v--;
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:46:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |   scanf("%d%d%d",&a,&b,&c);a--;b--;
      |   ~~~~~^~~~~~~~~~~~~~~~~~~

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