#include <bits/stdc++.h>
#define f0(i, n) for(int i(0); i < (n); i++)
#define f1(i, n) for(int i(1); i <= n; i++)
#define u first
#define v second
using namespace std;
typedef long long ll;
const int N = 100002;
int n, m, P;
map <pair <int, int>, int> g;
pair <int, int> ed[N];
vector <vector <int> > a;
/// cau
int num[N], low[N], cnt = 0;
/// disjoin set
int parent[N];
/// canh trong do thi moi
pair <int, int> newed[N];
/// dinh, canh trong do thi moi
int newdinh, newcanh;
/// dinh u thuoc dinh moi nao
int in[N];
/// lca
int f[N][17], h[N];
/// cung noi
int e1[N], e2[N];
map <pair <int, int>, char> Q;
map <pair <int, int>, int> cau;
int getroot(int u){
if(parent[u]==0) return u;
parent[u] = getroot(parent[u]);
return parent[u];
}
void join(int u, int v){
parent[getroot(v)] = getroot(u);
}
void dfs(int u, int p){
num[u] = low[u] = ++cnt;
for(auto v:a[u]){
if(v==p) continue;
if(num[v]) low[u] = min(low[u], num[v]);
else{
dfs(v, u);
low[u] = min(low[u], low[v]);
if(g[{u, v}]==1 && low[v] > num[u]){
newed[++newcanh] = {getroot(u), getroot(v)};
cau[{u, v}] = cau[{v, u}] = 1;
}
else{
join(u, v);
}
}
}
}
void timcau(){
f1(i, n){
if(num[i]==0) dfs(i, i);
}
map <int, int> thuoc; /// dinh u thuoc cha nao
f1(i, n){
int p = getroot(i);
if(thuoc[p]==0) thuoc[p] = ++newdinh;
in[i] = thuoc[p];
}
/// clear lai do thi cu
f1(i, n) a[i].clear();
f1(i, newcanh){
int u = newed[i].u, v = newed[i].v;
a[in[u]].emplace_back(in[v]);
a[in[v]].emplace_back(in[u]);
}
}
void dfs2(int u){
num[u] = 1;
for(auto v:a[u]){
if(num[v]) continue;
f[v][0] = u;
h[v] = h[u] + 1;
dfs2(v);
}
}
int lca(int u, int v){
if(h[u] < h[v]) swap(u, v);
for(int k = 16; k >= 0; k--){
if(h[u] - (1ll << k) >= h[v]) u = f[u][k];
}
if(u==v) return 1;
for(int k = 16; k >= 0; k--){
if(f[u][k] > 0 && f[v][k] > 0 && f[u][k] != f[v][k])
u = f[u][k], v = f[v][k];
}
return f[u][0];
}
void buildlca(){
/// dung lai ham num
f1(i, newdinh) num[i] = 0;
f1(i, newdinh){
if(num[i]==0){
dfs2(i);
}
}
f1(i, 16) f1(u, newdinh) f[u][i] = f[f[u][i - 1]][i - 1];
memset(e1, 0x3f3f3f, sizeof(e1));
memset(e2, 0x3f3f3f, sizeof(e2));
}
void add1(int u, int v){
/// noi u vao v
e1[u] = min(e1[u], h[v]);
}
void add2(int u, int v){
e2[u] = min(e2[u], h[v]);
}
void dfs3(int u){
num[u] = 1;
for(auto v:a[u]){
if(num[v]) continue;
dfs3(v);
if(e1[v] <= h[u]){
Q[{u, v}] = Q[{v, u}] = 'R';
}
e1[u] = min(e1[u], e1[v]);
}
}
void dfs4(int u){
num[u] = 1;
for(auto v:a[u]){
if(num[v]) continue;
dfs4(v);
if(e2[v] <= h[u]){
Q[{u, v}] = Q[{v, u}] = 'L';
}
e2[u] = min(e2[u], e2[v]);
}
}
void build(){
/// danh dau cac cung
memset(num, 0, sizeof(num));
f1(i, newdinh){
if(num[i]==0){
dfs3(i);
}
}
memset(num, 0, sizeof(num));
f1(i, newdinh){
if(num[i]==0){
dfs4(i);
}
}
}
int main(){
ios_base::sync_with_stdio(0);
cin >> n >> m;
a.resize(n + 1);
f1(i, m){
int u, v; cin >> u >> v;
ed[i] = {u, v};
a[u].emplace_back(v);
a[v].emplace_back(u);
g[{u, v}]++; g[{v, u}]++;
}
cin >> P;
timcau();
buildlca();
while(P--){
int u, v; cin >> u >> v;
/// u phai den v
int x = lca(in[u], in[v]);
add1(in[u], x);
add2(in[v], x);
}
build();
f1(i, m){
int u = ed[i].u, v = ed[i].v;
if(cau[{u, v}]){
if(Q.find({in[u], in[v]}) != Q.end()){
cout << Q[{in[u], in[v]}];
}
else cout << "B";
}
else cout << "B";
}
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
3 ms |
1528 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
3 ms |
1528 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
3 ms |
1528 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
