#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#define dbg(...) printf(__VA_ARGS__);
#define getchar_unlocked getchar
#else
#define dbg(...)
#endif
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define psf push_front
#define ppb pop_back
#define ppf pop_front
#define sz(x) (int)x.size()
#define mnto(x,y) x=min(x,(__typeof__(x))y)
#define mxto(x,y) x=max(x,(__typeof__(x))y)
#define INF 1023456789
#define LINF 1023456789123456789
#define all(x) x.begin(),x.end()
#define lb(x,v) (lower_bound(all(x),v)-x.begin())
#define ub(x,v) (upper_bound(all(x),v)-x.begin())
#define disc(x) sort(all(x));x.resize(unique(all(x))-x.begin());
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> iii;
typedef tuple<int,int,int,int> iiii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
mt19937 rng(time(0));
#define mod 1000000007
inline int add(int a,int b){
int r=a+b;
while(r>=mod)r-=mod;
while(r<0)r+=mod;
return r;
}
inline int mult(int a,int b){
return (int)(((ll)(a*b))%mod);
}
inline int rd(){
int x=0;
char ch=getchar_unlocked();
while(!(ch&16))ch=getchar_unlocked();//keep reading while current character is whitespace
while(ch&16){//this will break when ‘\n’ or ‘ ‘ is encountered
x=(x<<3)+(x<<1)+(ch&15);
ch=getchar_unlocked();
}
return x;
}
#define maxn 100005
int n,m,a[maxn],b[maxn],q,x[maxn],y[maxn];
int num[maxn],par[maxn],low[maxn],cnt,bridge[maxn];
int upar[maxn],bcnt,bcc[maxn];
int p[20][maxn],vis[maxn],dep[maxn];
ii to[maxn];
char ans[maxn];
stack<int> s;
vector<ii> AL[maxn],AL2[maxn];
void dfs(int u){
num[u]=low[u]=cnt++;
s.push(u);
for(auto[v,i]:AL[u]){
if(num[v]==-1){
par[v]=u;
dfs(v);
low[u]=min(low[u],low[v]);
if(low[v]>num[u]){
bridge[i]=true;
}
}
else if(v!=par[u]){
low[u]=min(low[u],num[v]);
}
}
}
int fp(int i){
return upar[i]==i?i:upar[i]=fp(upar[i]);
}
void join(int x,int y){
upar[fp(x)]=fp(y);
}
void dfs2(int u){
vis[u]=true;
for(int k=1;k<20;++k){
if(p[k-1][u]!=-1){
p[k][u]=p[k-1][p[k-1][u]];
}
}
for(auto[v,i]:AL2[u]){
if(p[0][u]==v)continue;
p[0][v]=u;
dep[v]=dep[u]+1;
dfs2(v);
}
}
int lca(int a,int b){
if(dep[a]>dep[b])swap(a,b);
for(int k=19;k>=0;--k){
if(p[k][a]!=-1&&dep[p[k][a]]>=dep[b])a=p[k][a];
}
if(a==b)return a;
for(int k=19;k>=0;--k){
if(p[k][a]!=p[k][b])a=p[k][a],b=p[k][b];
}
return p[0][a];
}
//returns dep to, dir
ii dfs3(int u){
ii res=to[u];
for(auto[v,i]:AL2[u]){
if(p[0][u]==v)continue;
ii pr=dfs3(v);
if(pr.fi<=dep[u]){
if(pr.se==0){//up
if(bcc[a[i]]==v)ans[i]='R';
else ans[i]='L';
}
else{//down
if(bcc[a[i]]==u)ans[i]='R';
else ans[i]='L';
}
}
else ans[i]='B';
res=min(res,pr);
}
return res;
}
int main(){
sf("%d%d",&n,&m);
for(int i=0;i<m;++i){
sf("%d%d",&a[i],&b[i]);
AL[a[i]].pb({b[i],i});
AL[b[i]].pb({a[i],i});
}
sf("%d",&q);
for(int i=0;i<q;++i){
sf("%d%d",&x[i],&y[i]);
}
memset(num,-1,sizeof num);
for(int i=1;i<=n;++i){
if(num[i]==-1){
dfs(i);
if(sz(AL[i])==1){
bridge[AL[i][0].se]=true;
}
}
upar[i]=i;
}
for(int i=0;i<m;++i){
if(!bridge[i]){
join(a[i],b[i]);
}
}
for(int i=1;i<=n;++i){
if(fp(i)==i)bcc[i]=bcnt++;
}
for(int i=1;i<=n;++i){
bcc[i]=bcc[fp(i)];
}
for(int i=0;i<m;++i){
if(bcc[a[i]]==bcc[b[i]]){
ans[i]='B';
}
else{
int u=bcc[a[i]],v=bcc[b[i]];
AL2[u].pb({v,i});
AL2[v].pb({u,i});
}
}
memset(p,-1,sizeof p);
for(int i=0;i<bcnt;++i){
if(!vis[i])dfs2(i);
to[i]={dep[i],2};
}
for(int i=0;i<q;++i){
int u=bcc[x[i]],v=bcc[y[i]];
int l=lca(u,v);
if(u!=l){
to[u]=min(to[u],{dep[l],0});//up
}
if(v!=l){
to[v]=min(to[v],{dep[l],1});//down
}
}
for(int i=0;i<bcnt;++i){
if(p[0][i]==-1)dfs3(i);
}
for(int i=0;i<m;++i)pf("%c",ans[i]);
pf("\n");
}
/*
5 6
1 2
1 2
4 3
2 3
1 3
5 1
2
4 5
1 3
*/
Compilation message
oneway.cpp: In function 'int main()':
oneway.cpp:149:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
149 | sf("%d%d",&n,&m);
| ^
oneway.cpp:151:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
151 | sf("%d%d",&a[i],&b[i]);
| ^
oneway.cpp:155:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
155 | sf("%d",&q);
| ^
oneway.cpp:157:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
157 | sf("%d%d",&x[i],&y[i]);
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
13268 KB |
Output is correct |
| 2 |
Incorrect |
5 ms |
13268 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
13268 KB |
Output is correct |
| 2 |
Incorrect |
5 ms |
13268 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
13268 KB |
Output is correct |
| 2 |
Incorrect |
5 ms |
13268 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
