#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define int long long
using namespace std;
int pow(int a,int b,int m){int ans=1;while(b){if(b&1){ans=(ans*a)%m;}b>>=1;a=(a*a)%m;}return ans;}
int binpow(int a,int b){int ans=1;while(b){if(b&1){ans=(ans*a);}b>>=1;a=(a*a);}return ans;}
const int N = 2e5 + 10, inf = 1e18;
int incyc[N], deg[N];
vector <int> g[N];
int lead[N];
int vis[N], par[N];
int tin[N], tout[N], up[N][25];
int timer;
void dfs(int v){
vis[v] = 1;
for(auto to : g[v]){
if(vis[to] == 0 && deg[to] > 1){
lead[to] = lead[v];
dfs(to);
}
}
}
void dfs2(int v, int p = 1) {
tin[v] = ++timer;
par[v] = p;
up[v][0] = p;
for (int i=1; i<=20; ++i)
up[v][i] = up[up[v][i-1]][i-1];
for (size_t i=0; i<g[v].size(); ++i) {
int to = g[v][i];
if (to == p)continue;
if(lead[to] == 0 || lead[to] == to)
dfs2 (to, v);
}
tout[v] = ++timer;
}
bool upper (int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int lca (int a, int b) {
if (upper (a, b)) return a;
if (upper (b, a)) return b;
for (int i=20; i>=0; --i)
if (! upper (up[a][i], b))
a = up[a][i];
return up[a][0];
}
int lift[N], desc[N];
main(){
iostream::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int n, m;
cin >> n >> m;
vector <pair <int,int> > road;
for(int i = 0; i < m; i++){
int a, b;
cin >> a >> b;
deg[a]++;
deg[b]++;
g[a].pb(b);
g[b].pb(a);
road.pb({a, b});
}
queue <int> q;
for(int i = 1; i <= n; i++){
if(deg[i] == 1)q.push(i);
}
while(!q.empty()){
int v = q.front();
q.pop();
for(auto to : g[v]){
if(--deg[to] == 1)q.push(to);
}
}
for(int i = 1; i <= n; i++){
if(deg[i] > 1 && lead[i] == 0){
lead[i] = i;
dfs(i);
}
}
for(int i = 1; i <= n; i++){
//cout << i <<"--" << lead[i]<< endl;
}
for(int i = 1; i <= n; i++){
if(lead[i] == 0 || lead[i] == i)continue;
for(auto to : g[i]){
if(lead[to] == 0){
g[lead[i]].pb(to);
g[to].pb(lead[i]);
}
}
}
for(int i = 1; i <= n; i++){
if(up[i][0] == 0 && (lead[i] == 0 || lead[i] == i)){
dfs2(i, i);
}
}
int p;
cin >> p;
while(p--){
int a, b;
cin >> a >> b;
//cout << lead[a] <<"="<< lead[b] << endl;
if(lead[a] != 0 && lead[a] != a)a = lead[a];
if(lead[b] != 0 && lead[b] != b)b = lead[b];
int lc = lca(a, b);
//cout << lc <<"-" << a <<" "<< b << endl;
while(a != lc){
// cout << a <<"->"<< par[a]<< endl;
if(par[a] == 0)return EXIT_FAILURE;
lift[a] = 1;
a = par[a];
}
while(b != lc){
if(par[b] == 0)return EXIT_FAILURE;
b = par[b];
desc[b] = 1;
}
}
for(auto x : road){
if(lead[x.ff] != 0 && lead[x.ff] == lead[x.ss]){
cout << 'B';
continue;
}
int f = x.ff, s = x.ss;
if(deg[f] > 1)f = lead[f];
if(deg[s] > 1)s = lead[s];
if(tin[f] < tin[s]){
if(desc[f]){
cout << 'R';
}else if(lift[s]){
cout << 'L';
}else
cout << 'B';
}else{
if(lift[f]){
cout << 'R';
}else if(desc[s]){
cout << 'L';
}else
cout << 'B';
}
}
}
Compilation message
oneway.cpp:64:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
64 | main(){
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
14680 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
14680 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
14680 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
