Submission #51970

#	Time	Username	Problem	Language	Result	Execution time	Memory
51970		TadijaSebez	Commuter Pass (JOI18_commuter_pass)	C++11	100 / 100	1352 ms	149040 KiB

commuter_pass

#include <stdio.h>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
#define mp make_pair
#define pb push_back
#define ll long long
const int N=100050;
vector<pair<int,int> > E[N];
vector<int> go[N];
ll dist[N],sol[N][3];
const ll inf=1e18;
bool ok[N];
bool mark[N];
void DFS(int u)
{
	mark[u]=1;
	for(int i=0;i<go[u].size();i++)
	{
		int v=go[u][i];
		if(!mark[v]) DFS(v);
	}
}
void Dijkstra1(int n, int s, int t)
{
	int i;
	for(i=1;i<=n;i++) dist[i]=inf,go[i].clear(),mark[i]=0;
	priority_queue<pair<ll,int> > pq;
	dist[s]=0;
	pq.push(mp(0,s));
	while(pq.size())
	{
		int u=pq.top().second;
		ll w=-pq.top().first;
		pq.pop();
		if(w!=dist[u]) continue;
		for(i=0;i<E[u].size();i++)
		{
			int v=E[u][i].first;
			w=E[u][i].second;
			if(dist[v]>dist[u]+w)
			{
				dist[v]=dist[u]+w;
				go[v].clear();
				pq.push(mp(-dist[v],v));
			}
			if(dist[v]==dist[u]+w) go[v].push_back(u);
		}
	}
	DFS(t);
	for(i=1;i<=n;i++) if(!mark[i]) go[i].clear();
}
ll Dijkstra2(int n, int s, int t)
{
	int i;
	for(i=1;i<=n;i++) sol[i][0]=sol[i][1]=sol[i][2]=inf;
	priority_queue<pair<ll,pair<int,int> > > pq;
	sol[s][0]=0;
	pq.push(mp(0,mp(s,0)));
	while(pq.size())
	{
		int u=pq.top().second.first;
		int t=pq.top().second.second;
		ll w=-pq.top().first;
		pq.pop();
		if(w!=sol[u][t]) continue;
		if(t==0 || t==2)
		{
			if(t==0 && sol[u][0]<sol[u][1])
			{
				sol[u][1]=sol[u][0];
				pq.push(mp(-sol[u][1],mp(u,1)));
			}
			for(i=0;i<E[u].size();i++)
			{
				int v=E[u][i].first;
				w=E[u][i].second;
				if(sol[v][t]>sol[u][t]+w)
				{
					sol[v][t]=sol[u][t]+w;
					pq.push(mp(-sol[v][t],mp(v,t)));
				}
			}
		}
		else if(t==1)
		{
			if(sol[u][1]<sol[u][2])
			{
				sol[u][2]=sol[u][1];
				pq.push(mp(-sol[u][2],mp(u,2)));
			}
			for(i=0;i<go[u].size();i++)
			{
				int v=go[u][i];
				if(sol[v][t]>sol[u][t])
				{
					sol[v][t]=sol[u][t];
					pq.push(mp(-sol[v][t],mp(v,t)));
				}
			}
		}
	}
	return sol[t][2];
}
ll min(ll a, ll b){ return a>b?b:a;}
int main()
{
	int n,m,u,v,w,i,a,b,s,t;
	scanf("%i %i",&n,&m);
	scanf("%i %i",&s,&t);
	scanf("%i %i",&a,&b);
	while(m--) scanf("%i %i %i",&u,&v,&w),E[u].pb(mp(v,w)),E[v].pb(mp(u,w));
	Dijkstra1(n,t,s);
	ll ans=Dijkstra2(n,a,b);
	ans=min(ans,Dijkstra2(n,b,a));
	Dijkstra1(n,t,s);
	ans=min(ans,Dijkstra2(n,a,b));
	ans=min(ans,Dijkstra2(n,b,a));
	printf("%lld\n",ans);
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void DFS(int)':
commuter_pass.cpp:19:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<go[u].size();i++)
              ~^~~~~~~~~~~~~
commuter_pass.cpp: In function 'void Dijkstra1(int, int, int)':
commuter_pass.cpp:38:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(i=0;i<E[u].size();i++)
           ~^~~~~~~~~~~~
commuter_pass.cpp: In function 'long long int Dijkstra2(int, int, int)':
commuter_pass.cpp:75:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(i=0;i<E[u].size();i++)
            ~^~~~~~~~~~~~
commuter_pass.cpp:93:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(i=0;i<go[u].size();i++)
            ~^~~~~~~~~~~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:109:16: warning: unused variable 'i' [-Wunused-variable]
  int n,m,u,v,w,i,a,b,s,t;
                ^
commuter_pass.cpp:110:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
commuter_pass.cpp:111:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&s,&t);
  ~~~~~^~~~~~~~~~~~~~~
commuter_pass.cpp:112:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&a,&b);
  ~~~~~^~~~~~~~~~~~~~~
commuter_pass.cpp:113:56: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  while(m--) scanf("%i %i %i",&u,&v,&w),E[u].pb(mp(v,w)),E[v].pb(mp(u,w));
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

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