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Submission #129970

# Submission time Handle Problem Language Result Execution time Memory
129970 2019-07-13T16:52:01 Z TadijaSebez One-Way Streets (CEOI17_oneway) C++11
100 / 100
 244 ms 29868 KB 
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int N=100050;
const int L=17;
vector<pair<int,int>> G[N];
vector<pair<int,int>> edges;
stack<int> s;
bool in[N];
int disc[N],low[N],tid;
int csz,comp[N];
void Tarjan(int u, int p)
{
	disc[u]=low[u]=++tid;
	s.push(u);in[u]=1;
	for(int i=0;i<G[u].size();i++) if(G[u][i].second!=p)
	{
		int v=G[u][i].first;
		if(!disc[v])
		{
			Tarjan(v,G[u][i].second);
			low[u]=min(low[u],low[v]);
		}
		else if(in[v]) low[u]=min(low[u],disc[v]);
	}
	if(disc[u]==low[u])
	{
		int v;
		csz++;
		do
		{
			v=s.top();
			s.pop();
			in[v]=0;
			comp[v]=csz;
		}while(v!=u);
	}
}
vector<pair<int,int>> E[N];
int up[N],par[N][L],dep[N];
int mnu[N],mnd[N];
void DFS(int u, int p)
{
	dep[u]=dep[p]+1;
	par[u][0]=p;
	for(int i=1;i<L;i++) par[u][i]=par[par[u][i-1]][i-1];
	mnu[u]=mnd[u]=1e9+7;
	for(auto e:E[u]) if(e.first!=p)
	{
		up[e.first]=e.second;
		DFS(e.first,u);
	}
}
int LCA(int u, int v)
{
	if(dep[u]<dep[v]) swap(u,v);
	for(int i=L-1;~i;i--) if(dep[par[u][i]]>=dep[v]) u=par[u][i];
	for(int i=L-1;~i;i--) if(par[u][i]!=par[v][i]) u=par[u][i],v=par[v][i];
	return u==v?v:par[v][0];
}
int ans[N];
void Solve(int u, int p)
{
	for(auto e:E[u]) if(e.first!=p)
	{
		int v=e.first;
		Solve(v,u);
		mnd[u]=min(mnd[u],mnd[v]);
		mnu[u]=min(mnu[u],mnu[v]);
	}
	if(mnu[u]<dep[u])
	{
		if(up[u]>0) ans[up[u]]=-1;
		else ans[-up[u]]=1;
	}
	if(mnd[u]<dep[u])
	{
		if(up[u]>0) ans[up[u]]=1;
		else ans[-up[u]]=-1;
	}
}
int main()
{
	int n,m,u,v;
	scanf("%i %i",&n,&m);
	for(int i=1;i<=m;i++)
	{
		scanf("%i %i",&u,&v);
		G[u].pb({v,i});
		G[v].pb({u,i});
		edges.pb({u,v});
	}
	vector<int> root;
	for(int i=1;i<=n;i++) if(!disc[i]) Tarjan(i,0),root.pb(csz);
	for(int i=0;i<m;i++)
	{
		u=edges[i].first;
		v=edges[i].second;
		if(comp[u]!=comp[v])
		{
			E[comp[u]].pb({comp[v],i+1});
			E[comp[v]].pb({comp[u],-(i+1)});
		}
	}
	for(int r:root) DFS(r,0);
	int q;
	scanf("%i",&q);
	while(q--)
	{
		scanf("%i %i",&u,&v);
		u=comp[u];
		v=comp[v];
		int lca=LCA(u,v);
		mnu[u]=min(mnu[u],dep[lca]);
		mnd[v]=min(mnd[v],dep[lca]);
	}
	for(int r:root) Solve(r,0);
	for(int i=1;i<=m;i++)
	{
		if(ans[i]==0) printf("B");
		else if(ans[i]==1) printf("R");
		else printf("L");
	}
	return 0;
}

Compilation message

oneway.cpp: In function 'void Tarjan(int, int)':
oneway.cpp:16:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<G[u].size();i++) if(G[u][i].second!=p)
              ~^~~~~~~~~~~~
oneway.cpp: In function 'int main()':
oneway.cpp:85:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:88:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%i %i",&u,&v);
   ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:107:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i",&q);
  ~~~~~^~~~~~~~~
oneway.cpp:110:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%i %i",&u,&v);
   ~~~~~^~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5116 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 7 ms 5244 KB Output is correct
5 Correct 7 ms 5240 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 7 ms 5240 KB Output is correct
8 Correct 7 ms 5240 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 7 ms 5116 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5116 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 7 ms 5244 KB Output is correct
5 Correct 7 ms 5240 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 7 ms 5240 KB Output is correct
8 Correct 7 ms 5240 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 7 ms 5116 KB Output is correct
11 Correct 62 ms 11344 KB Output is correct
12 Correct 73 ms 12396 KB Output is correct
13 Correct 80 ms 13800 KB Output is correct
14 Correct 96 ms 16980 KB Output is correct
15 Correct 102 ms 18408 KB Output is correct
16 Correct 137 ms 24188 KB Output is correct
17 Correct 114 ms 25800 KB Output is correct
18 Correct 142 ms 24392 KB Output is correct
19 Correct 111 ms 26860 KB Output is correct
20 Correct 70 ms 11932 KB Output is correct
21 Correct 66 ms 12008 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5116 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Correct 7 ms 5244 KB Output is correct
5 Correct 7 ms 5240 KB Output is correct
6 Correct 6 ms 5112 KB Output is correct
7 Correct 7 ms 5240 KB Output is correct
8 Correct 7 ms 5240 KB Output is correct
9 Correct 7 ms 5112 KB Output is correct
10 Correct 7 ms 5116 KB Output is correct
11 Correct 62 ms 11344 KB Output is correct
12 Correct 73 ms 12396 KB Output is correct
13 Correct 80 ms 13800 KB Output is correct
14 Correct 96 ms 16980 KB Output is correct
15 Correct 102 ms 18408 KB Output is correct
16 Correct 137 ms 24188 KB Output is correct
17 Correct 114 ms 25800 KB Output is correct
18 Correct 142 ms 24392 KB Output is correct
19 Correct 111 ms 26860 KB Output is correct
20 Correct 70 ms 11932 KB Output is correct
21 Correct 66 ms 12008 KB Output is correct
22 Correct 244 ms 26844 KB Output is correct
23 Correct 204 ms 25324 KB Output is correct
24 Correct 211 ms 25580 KB Output is correct
25 Correct 229 ms 29868 KB Output is correct
26 Correct 213 ms 26600 KB Output is correct
27 Correct 198 ms 25448 KB Output is correct
28 Correct 71 ms 9068 KB Output is correct
29 Correct 113 ms 12792 KB Output is correct
30 Correct 112 ms 13032 KB Output is correct
31 Correct 116 ms 13216 KB Output is correct
32 Correct 163 ms 18668 KB Output is correct