#include<bits/stdc++.h>
using namespace std;
#define range(v) begin(v), end(v)
#define compact(v) v.erase(unique(range(v)), end(v))
template<class T> bool minimize(T& a, T b){
if(a > b) return a = b, true;
return false;
}
template<class T> bool maximize(T& a, T b){
if(a < b) return a = b, true;
return false;
}
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const int N = 1e5 + 5;
const int Left = 0;
const int Right = 1;
const int Both = 2;
const char c[] = {'L', 'R', 'B'};
int n, m, low[N], num[N], id[N], timerDFS, timerSCC;
pair<int, int> e[N], E[N];
vector<pair<int, int>> g[N], G[N];
stack<int> stck;
void dfsTarjan(int u, int preID){
low[u] = num[u] = ++timerDFS;
stck.push(u);
for(auto [id, dir] : g[u]) if(id != preID){
int v = e[id].first ^ e[id].second ^ u;
if(num[v]) {
minimize(low[u], num[v]);
}
else{
dfsTarjan(v, id);
minimize(low[u], low[v]);
}
}
if(low[u] == num[u]){
++timerSCC;
do{
int v = stck.top(); stck.pop();
id[v] = timerSCC;
low[u] = num[u] = N;
} while(!id[u]);
}
}
int ans[N], node[N], st[N << 2], lzy[N << 2], h[N], head[N], par[N], pos[N], sz[N], heavy[N], parID[N], ptr[N], timerHLD;
void dfsSize(int u, int preID){
sz[u] = 1;
heavy[u] = 0;
for(auto [id, dir] : G[u]) if(id != preID){
int v = u ^ E[id].first ^ E[id].second;
h[v] = h[u] + 1;
par[v] = u;
parID[v] = id;
dfsSize(v, id);
sz[u] += sz[v];
if(sz[heavy[u]] < sz[v]){
heavy[u] = v;
}
}
}
void decompose(int u, int curHead){
head[u] = curHead;
if(heavy[u]){
node[pos[heavy[u]] = ++timerHLD] = heavy[u];
decompose(heavy[u], curHead);
for(auto [id, dir] : G[u]){
int v = u ^ E[id].first ^ E[id].second;
if(v != par[u] and v != heavy[u]){
node[pos[v] = ++timerHLD] = v;
decompose(v, v);
}
}
}
}
void apply(int id, int val){
st[id] = val;
lzy[id] = val;
}
void pushDown(int id){
if(lzy[id] != -1){
apply(id << 1, lzy[id]);
apply(id << 1 | 1, lzy[id]);
lzy[id] = -1;
}
}
void update(int id, int l, int r, int u, int v, int target){
if(v < l or u > r or l > r) return;
if(u <= l and r <= v){
apply(id, target);
}
else{
int mid = l + r >> 1;
pushDown(id);
update(id << 1, l, mid, u, v, target);
update(id << 1 | 1, mid + 1, r, u, v, target);
}
}
void get(int id, int l, int r){ //compute after preprocessed
if(l < r){
int mid = l + r >> 1;
pushDown(id);
get(id << 1, l, mid);
get(id << 1 | 1, mid + 1, r);
}
else ptr[node[l]] = st[id];
}
int getLCA(int u, int v){
while(head[u] != head[v]){
if(h[head[u]] < h[head[v]]) swap(u, v);
u = par[head[u]];
}
return h[u] < h[v] ? u : v;
}
void updatePath(int u, int v, int target){
while(head[u] != head[v]){
if(h[head[u]] < h[head[v]]) swap(u, v);
update(1, 1, timerSCC - 1, pos[head[u]], pos[u], target);
}
if(h[u] > h[v]) swap(u, v);
update(1, 1, timerSCC - 1, pos[u] + 1, pos[v], target);
}
void Zero_OP(){
cin >> n >> m;
for(int i = 1; i <= m; ++i){
int u, v;
cin >> u >> v;
g[u].push_back({i, 0});
g[v].push_back({i, 1});
e[i] = {u, v};
}
dfsTarjan(1, -1);
for(int i = 1; i <= m; ++i){
int u, v;
tie(u, v) = e[i];
E[i] = {id[u], id[v]};
if(id[u] != id[v]){
G[id[u]].push_back({i, 0});
G[id[v]].push_back({i, 1});
}
else ans[i] = Both;
}
dfsSize(1, -1);
decompose(1, -1);
memset(lzy, -1, sizeof(lzy));
memset(st, -1, sizeof(st));
int q; cin >> q;
for(int i = 1; i <= q; ++i){
int u, v;
cin >> u >> v;
u = id[u], v = id[v];
int mid = getLCA(u, v);
updatePath(u, mid, Left);
updatePath(mid, v, Right);
}
get(1, 1, timerSCC - 1);
for(int i = 2; i <= timerSCC; ++i){
int g = parID[i];
int target = ptr[i];
if(target == -1) ans[g] = Both;
else{
ans[g] = target;
if(E[g].first != par[E[g].second]) ans[g] ^= 1;
}
}
for(int i = 1; i <= m; ++i){
cout << c[ans[i]];
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
#define task "antuvu"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
Zero_OP();
return 0;
}
Compilation message
oneway.cpp: In function 'void update(int, int, int, int, int, int)':
oneway.cpp:108:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
108 | int mid = l + r >> 1;
| ~~^~~
oneway.cpp: In function 'void get(int, int, int)':
oneway.cpp:117:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
117 | int mid = l + r >> 1;
| ~~^~~
oneway.cpp: In function 'int main()':
oneway.cpp:204:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
204 | freopen(task".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp:205:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
205 | freopen(task".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
3043 ms |
11868 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
3043 ms |
11868 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
3043 ms |
11868 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
