#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
#include <random>
using namespace std;
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << "[" << H << "]";
debug_out(T...);
}
#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)
clock_t startTime;
double getCurrentTime() {
return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}
#define MP make_pair
typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const double eps = 0.000001;
const int MOD = 1e9 + 7;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 1e6 + 3e2;
const int M = 1111;
int eu[N], ev[N];
vector<int> g[N];
int flag[N];
bool used[N];
set<pair<int, int>> bridges;
set<pair<int, int>> trash;
void bridge(int x, int y){
if (trash.count(MP(x, y))) return;
if (trash.count(MP(y, x))) return;
bridges.insert(MP(x, y));
}
int tin[N], fup[N], timer = 0;
void dfs(int v, int p){
tin[v] = fup[v] = ++timer;
used[v] = true;
for (int u : g[v]){
if (u == p) continue;
if (!used[u]){
dfs(u, v);
fup[v] = min(fup[v], fup[u]);
if (fup[u] > tin[v]) bridge(u, v);
} else {
fup[v] = min(fup[v], tin[u]);
}
}
}
int p[N];
int find(int x){
return (x == p[x] ? x : p[x] = find(p[x]));
}
void unite(int x, int y){
x = find(x);
y = find(y);
if (rng() & 1) swap(x, y);
p[x] = y;
}
void bfs(int x, vector<int> &d){
queue<int> q;
fill(all(d), INF);
d[x] = 0;
q.push(x);
while (!q.empty()){
x = q.front();
q.pop();
for (int y : g[x]){
if (d[y] == INF){
d[y] = d[x] + 1;
q.push(y);
}
}
}
}
map<pair<int, int>, int> mp;
void SetLeft(int x, int y){
int i = mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)];
flag[i] = 1;
}
void SetRight(int x, int y){
int i = mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)];
flag[i] = 2;
}
void solve(int TC) {
int n, m;
cin >> n >> m;
for (int i = 1; i <= m; i++){
int x, y;
cin >> x >> y;
eu[i] = x, ev[i] = y;
if (mp.count(MP(x, y))){
int ii = (mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)]);
flag[i] = flag[ii] = 3;
trash.insert(MP(x, y));
continue;
}
if (x == y){
flag[i] = 3;
continue;
}
mp[MP(x, y)] = i;
g[x].push_back(y);
g[y].push_back(x);
}
int q;
cin >> q;
vector<pair<int, int>> important;
while (q--){
int x, y;
cin >> x >> y;
important.emplace_back(x, y);
}
dfs(1, 1);
for (int i = 1; i <= m; i++){
int x = eu[i], y = ev[i];
if (!bridges.count(MP(x, y))) flag[i] = 3;
}
auto _br = bridges;
bridges.clear();
for (auto now : _br){
if (mp.find(now) == mp.end()) swap(now.first, now.second);
bridges.insert(now);
// cout << now.first << ' ' << now.second << endl;
}
iota(p + 1, p + n + 1, 1);
for (int i = 1; i <= m; i++){
if (flag[i] == 3) unite(eu[i], ev[i]);
}
for (int i = 1; i <= n; i++) g[i].clear();
int root = n;
// cout << endl;
// for (int i = 1; i <= n; i++) cout << find(i) << ' ';
// cout << endl << endl;
for (int i = 1; i <= m; i++){
int x = find(eu[i]), y = find(ev[i]);
root = min({root, x, y});
if (x != y){
g[x].push_back(y);
g[y].push_back(x);
// cout << "edge " << x << ' ' << y << endl;
}
}
for (auto [x, y] : important){
int X = x, Y = y;
x = find(x), y = find(y);
if (x == y) continue;
vector<int> dx(n + 1), dy(n + 1);
bfs(x, dx);
bfs(y, dy);
for (auto [u, v] : bridges){
int U = u, V = v;
// cout << X << ' ' << Y << ' ' << U << ' ' << V << endl;
// cout << dx[u] << ' ' << dy[v] << endl;
u = find(u), v = find(v);
int dist = min(dx[u] + dy[v], dx[v] + dy[u]) + 1;
if (dist != dx[y]) continue;
if (dx[u] + dy[v] + 1 == dist){ // x -> u -> v -> y
// cout << "R " << X << ' ' << U << ' ' << V << ' ' << Y << endl;
SetRight(U, V);
} else { // x -> v -> u -> y
// cout << "L " << X << ' ' << V << ' ' << U << ' ' << Y << endl;
SetLeft(U, V);
}
}
}
for (int i = 1; i <= m; i++){
if (flag[i] == 0 || flag[i] == 3) cout << 'B';
if (flag[i] == 1) cout << 'L';
if (flag[i] == 2) cout << 'R';
}
}
int main() {
startTime = clock();
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#ifdef dddxxz
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
int TC = 1;
// cin >> TC;
for (int test = 1; test <= TC; test++) {
//debug(test);
//cout << "Case #" << test << ": ";
solve(test);
}
#ifdef dddxxz
cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;
#endif
return 0;
}
Compilation message
oneway.cpp: In function 'void solve(int)':
oneway.cpp:204:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
204 | for (auto [x, y] : important){
| ^
oneway.cpp:214:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
214 | for (auto [u, v] : bridges){
| ^
oneway.cpp:205:13: warning: unused variable 'X' [-Wunused-variable]
205 | int X = x, Y = y;
| ^
oneway.cpp:205:20: warning: unused variable 'Y' [-Wunused-variable]
205 | int X = x, Y = y;
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
15 ms |
23764 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
15 ms |
23764 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
15 ms |
23764 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
