Submission #47726

#	Time	Username	Problem	Language	Result	Execution time	Memory
47726		dqhungdl	Evacuation plan (IZhO18_plan)	C++17	100 / 100	1221 ms	46536 KiB

plan

#include <bits/stdc++.h>
using namespace std;
 
const int MAX=17;
typedef pair<int,int> ii;
int n,m,k,T,d[100005],R[100005],S[100005],h[100005],P[100005][20],mind[100005][20];
vector<ii> Edge,g[100005],gg[100005];
set<ii> s;
 
bool cmp(ii x1,ii x2)
{
	return min(d[x1.first],d[x1.second])>min(d[x2.first],d[x2.second]);
}
 
int Find(int u)
{
	if(u==R[u])
		return u;
	return R[u]=Find(R[u]);
}
 
void Union(int u,int v)
{
	if(S[u]>S[v])
	{
		S[u]+=S[v];
		R[v]=u;
	}
	else
	{
		S[v]+=S[u];
		R[u]=v;
	}
}
 
void Enter()
{
	cin>>n>>m;
	int u,v,w;
	while(m--)
	{
		cin>>u>>v>>w;
		Edge.push_back(ii(u,v));
		g[u].push_back(ii(v,w));
		g[v].push_back(ii(u,w));
	}
	for(int i=1;i<=n;i++)
	{
		d[i]=1e9;
		R[i]=i;
	}
	cin>>k;
	while(k--)
	{
		cin>>u;
		s.insert(ii(0,u));
		d[u]=0;
	}
}
 
void BFS()
{
	while(s.size()>0)
	{
		int u=(*s.begin()).second;
		s.erase(s.begin());
		for(int i=0;i<g[u].size();i++)
		{
			int v=g[u][i].first;
			int w=g[u][i].second;
			if(d[v]>d[u]+w)
			{
				if(d[v]!=1e9)
					s.erase(s.find(ii(d[v],v)));
				d[v]=d[u]+w;
				s.insert(ii(d[v],v));
			}
		}
	}
}
 
void DFS(int u,int high)
{
	h[u]=high;
	for(int i=0;i<gg[u].size();i++)
	{
		int v=gg[u][i].first;
		int w=gg[u][i].second;
		if(h[v]==0)
		{
			P[v][0]=u;
			mind[v][0]=w;
			DFS(v,high+1);					
		}
	}
}
 
int LCA(int u,int v)
{
	int rs=1e9;
    for(int k=MAX;k>=0;k--)
        if(h[P[u][k]]>=h[v])
        {
        	rs=min(rs,mind[u][k]);
            u=P[u][k];         
        }
        else
        if(h[P[v][k]]>=h[u])
        {
        	rs=min(rs,mind[v][k]);
            v=P[v][k];
        }
    for(int k=MAX;k>=0;k--)
        if(P[u][k]!=P[v][k])
        {
        	rs=min(rs,mind[u][k]);
        	rs=min(rs,mind[v][k]);
            u=P[u][k];
            v=P[v][k];
        }
    while(u!=v)
    {
    	rs=min(rs,mind[u][0]);
        rs=min(rs,mind[v][0]);
        u=P[u][0];
        v=P[v][0];
    }
    return rs;
}
 
void InitTree()
{
	sort(Edge.begin(),Edge.end(),cmp);
	for(int i=0;i<Edge.size();i++)
	{
		int u=Edge[i].first;
		int v=Edge[i].second;
		int w=min(d[u],d[v]);
		if(Find(u)!=Find(v))
		{
			Union(Find(u),Find(v));
			gg[u].push_back(ii(v,w));
			gg[v].push_back(ii(u,w));
		}
	}
	DFS(1,1);
	for(int k=1;k<=MAX;k++)
    	for(int i=1;i<=n;i++)
    	{
			P[i][k]=P[P[i][k-1]][k-1];
			mind[i][k]=min(mind[i][k-1],mind[P[i][k-1]][k-1]);
    	}
}
 
void Query()
{
	cin>>T;
	int u,v;
	while(T--)
	{
		cin>>u>>v;
		cout<<LCA(u,v)<<"\n";
	}
}
 
int main()
{
	ios_base::sync_with_stdio(false);
	//freopen("TEST.INP","r",stdin);
	//freopen("TEST.OUT","w",stdout);
	Enter();
	BFS();
	InitTree();
	Query();
}

Compilation message (stderr)

plan.cpp: In function 'void BFS()':
plan.cpp:67:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[u].size();i++)
               ~^~~~~~~~~~~~
plan.cpp: In function 'void DFS(int, int)':
plan.cpp:85:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<gg[u].size();i++)
              ~^~~~~~~~~~~~~
plan.cpp: In function 'void InitTree()':
plan.cpp:134:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<Edge.size();i++)
              ~^~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46