#include<bits/stdc++.h>
#define lcm(a,b) (a/__gcd(a,b))*b
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long int
#define vi vector<int>
#define vll vector<ll>
#define pb push_back
#define F first
#define S second
#define mp make_pair
using namespace std;
const int MA=1e5+5;
vector<pair<int,int> > G[MA];
int vis[MA];
int arc[MA];
int num=0;
set<pair<int,int> >st;
int puente[MA];
int depth[MA];
string res;
int dp[21][MA];
void tarjan(int nodo, int ant){
num++;
vis[nodo]=arc[nodo]=num;
for(int it =0;it<G[nodo].size();it++){
int to=G[nodo][it].F,ind=G[nodo][it].S;
if(ind==ant)continue;
if(vis[to]==0){
tarjan(to,ind);
if(arc[to]>vis[nodo]){
puente[ind]=1;
}
arc[nodo]=min(arc[nodo],arc[to]);
}else{
arc[nodo]=min(arc[nodo],vis[to]);
}
}
}
vector<pair<int,int> > G2[MA];
int C[MA];
int color=0;
void coloring(int nodo){
C[nodo]=color;
for(int i=0;i<G[nodo].size();i++){
int to=G[nodo][i].F,ind=G[nodo][i].S;
if(puente[ind] or C[to])continue;
coloring(to);
}
}
int sgt[MA];
void init(int nodo, int padre){
dp[0][nodo]=padre;
for(int i=0;i<G2[nodo].size();i++){
int it=G2[nodo][i].F,ind=G2[nodo][i].S;
if(it!=padre){
depth[it]=depth[nodo]+1;
sgt[it]=ind;
init(it,nodo);
}
}
}
void initlca(){
depth[1]=1;
init(1,-1);
for(int i=1;i<20;i++){
for(int l=1;l<=color;l++){
if(dp[i-1][l]==-1)continue;
dp[i][l]=dp[1-1][dp[i-1][l]];
}
}
}
int LCA(int a, int b){
if(depth[a]>depth[b])swap(a,b);
//tengo que igualar alturas
int dif=depth[b]-depth[a];
for(int i=0;i<20;i++){
if((1<<i)&dif){
b==dp[i][b];
}
}
if(a==b)return a;
for(int i=19;i>=0;i--){
if(dp[i][a]==dp[i][b])continue;
a=dp[i][a];
b=dp[i][b];
}
return dp[0][a];//uno arribita
}
int main()
{
int n,m,p,a,b;
cin>>n>>m;
vector<pair<int,int> >E;
for(int i=0;i<m;i++){
cin>>a>>b;
G[a].pb({b,i});G[b].pb({a,i});
E.pb({a,b});
}
res.assign(m,'B');
for(int i=1;i<=n;i++){
if(vis[i]==0){
tarjan(i,-1);
}
}
for(int i=1;i<=n;i++){
if(C[i])continue;
color++;
coloring(i);
}
for(int i=0;i<m;i++){
if(puente[i]==0)continue;
int A=C[E[i].F],B=C[E[i].S];
G2[A].pb({B,i});
G2[B].pb({A,i});
}
initlca();
cin>>p;
for(int i=0;i<p;i++){
cin>>a>>b;
a=C[a],b=C[b];
if(a==b)continue;
int lca=LCA(a,b);
//cout<<"lca "<<a<<" "<<b<<" "<<lca<<endl;
int nodo=a;
while(nodo!=lca){
int ind=sgt[nodo];
if(res[ind]!='B')break;
//cout<<"indice "<<ind<<endl;
int pa=C[E[ind].S];
if(pa!=nodo){
res[ind]='R';
}else{
pa=C[E[ind].F];
res[ind]='L';
}
nodo=pa;
}
nodo=b;
while(nodo!=lca){
int ind=sgt[nodo];
if(res[ind]!='B')break;
int pa=C[E[ind].S];
if(pa!=nodo){
res[ind]='L';
}else{
pa=C[E[ind].F];
res[ind]='R';
}
nodo=pa;
}
}
cout<<res<<endl;
return 0;
}
Compilation message
oneway.cpp: In function 'void tarjan(int, int)':
oneway.cpp:25:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
25 | for(int it =0;it<G[nodo].size();it++){
| ~~^~~~~~~~~~~~~~~
oneway.cpp: In function 'void coloring(int)':
oneway.cpp:44:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
44 | for(int i=0;i<G[nodo].size();i++){
| ~^~~~~~~~~~~~~~~
oneway.cpp: In function 'void init(int, int)':
oneway.cpp:53:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
53 | for(int i=0;i<G2[nodo].size();i++){
| ~^~~~~~~~~~~~~~~~
oneway.cpp: In function 'int LCA(int, int)':
oneway.cpp:79:14: warning: statement has no effect [-Wunused-value]
79 | b==dp[i][b];
| ~^~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
5068 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
5068 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
3 ms |
5068 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
