#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], fup[N], h[N];
vector <int> g[N], gc[N];
int lead[N];
int vis[N], par[N];
int tin[N], tout[N], up[N][25], used[N];
int timer;
map <pair <int,int>, int > brid;
void dfsc(int v){
vis[v] = 1;
for(auto to : g[v]){
if(vis[to] == 0 && !brid.count({v, to})){
lead[to] = lead[v];
dfsc(to);
}
}
}
void dfs2(int v, int p = 1) {
//cout << v <<" p"<< p << endl;
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<gc[v].size(); ++i) {
int to = gc[v][i];
if (to == p)continue;
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];
void dfs (int v, int p = -1) {
used[v] = true;
tin[v] = fup[v] = timer++;
for (size_t i=0; i<g[v].size(); ++i) {
int to = g[v][i];
if (to == p) continue;
if (used[to])
fup[v] = min (fup[v], tin[to]);
else {
dfs (to, v);
fup[v] = min (fup[v], fup[to]);
if (fup[to] > tin[v]){
brid[{v, to}] = 1;
brid[{to, v}] = 1;
}
}
}
}
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;
g[a].pb(b);
g[b].pb(a);
road.pb({a, b});
}
dfs(1);
//cout << "fin" << endl;
for(int i = 1; i <= n; i++){
if(lead[i] == 0){
lead[i] = i;
dfsc(i);
}
}
//cout << "fin2" << endl;
for(int i = 1; i <= n; i++){
for(auto to : g[i]){
if(brid.count({i, to})){
//cout << lead[i] <<"-"<< lead[to] << endl;
gc[lead[i]].pb(lead[to]);
}
}
}
for(int i = 1; i <= n; i++){
if(par[lead[i]] == 0){
//cout <<"notvis" << lead[i] << endl;
dfs2(lead[i], lead[i]);
}
}
int p;
cin >> p;
map <pair <int,int>, int> mp;
while(p--){
int a, b;
cin >> a >> b;
a = lead[a];
b = lead[b];
int lc = lca(a, b);
//cout << a <<" "<< b <<" "<< lc << endl;
while(a != lc){
//cout << a <<"->"<< par[a]<< endl;
if(par[a] == 0)return EXIT_FAILURE;
mp[{a, par[a]}] = 1;
lift[a] = 1;
a = par[a];
}
while(b != lc){
if(par[b] == 0)return EXIT_FAILURE;
//cout << b <<" " << par[b]<< endl;
mp[{par[b], b}] = 1;
desc[b] = 1;
b = par[b];
}
}
for(auto x : road){
int f = x.ff, s = x.ss;
f = lead[f];
s = lead[s];
if(mp.count({f, s}))
cout << 'R';
else if(mp.count({s, f}))
cout << 'L';
else
cout << 'B';
}
}
Compilation message
oneway.cpp:84:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
84 | main(){
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
25348 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
25348 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
5 ms |
25348 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
