#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
random_device(rd);
mt19937 rng(rd());
const long long FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
struct custom_hash
{
template<class T>
unsigned long long operator()(T v) const
{
unsigned long long x = v;
x += FIXED_RANDOM;
// x += 11400714819323198485ull;
// x = (x ^ (x >> 30)) * 13787848793156543929ull;
x = (x ^ (x >> 27)) * 10723151780598845931ull;
return x ^ (x >> 31);
}
};
template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T, class U> using hash_table = gp_hash_table<T, U, custom_hash>;
template<class T>
T randomize(T mod)
{
return (uniform_int_distribution<T>(0, mod - 1))(rng);
}
template<class T>
void readi(T &x)
{
x = 0;
bool negative = false;
char c = ' ';
while (c < '-')
{
c = getchar();
}
if (c == '-')
{
negative = true;
c = getchar();
}
while (c >= '0')
{
x = x * 10 + (c - '0');
c = getchar();
}
if (negative)
{
x = -x;
}
}
template<class T>
void printi(T output)
{
if (output == 0)
{
putchar('0');
return;
}
if (output < 0)
{
putchar('-');
output = -output;
}
int buf[20], n = 0;
while(output)
{
buf[n] = ((output % 10));
output /= 10;
n++;
}
for (n--; n >= 0; n--)
{
putchar(buf[n] + '0');
}
return;
}
template<class T>
void ckmin(T &a, T b)
{
a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
a = max(a, b);
}
long long expo(long long a, long long e, long long mod)
{
return ((e == 0) ? 1 : ((expo(a * a % mod, e >> 1, mod)) * ((e & 1) ? a : 1) % mod));
}
template<class T, class U>
void nmod(T &x, U mod)
{
if (x >= mod) x -= mod;
}
template<class T>
T gcd(T a, T b)
{
return (b ? gcd(b, a % b) : a);
}
#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define DBG(x) cerr << #x << " = " << (x) << endl
#define SZ(x) ((int) ((x).size()))
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
#define ALL(x) (x).begin(), (x).end()
const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-9;
#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 100013
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<ld> vd;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
typedef vector<pdd> vpd;
int N, M, K, T;
vi edge[MAXN], edge1[MAXN];
int res[MAXN], ans[MAXN];
vpi needs;
int dsu[MAXN];
int disc[MAXN], low[MAXN], parent[MAXN], depth[MAXN], st[MAXN], ft[MAXN];
int ancestor[22][MAXN];
bitset<MAXN> seen;
hash_table<int, int> eid[MAXN], bridge[MAXN];
hash_table<int, vi> dup[MAXN];
vi bcc[MAXN];
int ups[22][MAXN];
vpi edges;
int get(int u)
{
return (u == dsu[u] ? u : dsu[u] = get(dsu[u]));
}
void merge(int u, int v)
{
u = get(u);
v = get(v);
if (u == v) return;
dsu[u] = v;
return;
}
void dfs(int u, bool head = false)
{
disc[u] = T;
low[u] = T;
seen[u] = true;
T++;
for (int v : edge[u])
{
if (v == parent[u]) continue;
edges.PB({u, v});
if (seen[v])
{
ckmin(low[u], disc[v]);
continue;
}
parent[v] = u;
dfs(v);
ckmin(low[u], low[v]);
if (low[v] >= disc[u] || head)
{
if (low[v] != disc[u])
{
bridge[u][v] = true;
bridge[v][u] = true;
}
}
}
}
void dfs1(int u)
{
st[u] = T;
ft[u] = T;
T++;
for (int v : edge1[u])
{
if (v == parent[u]) continue;
// cerr << u << " -> " << v << endl;
parent[v] = u;
depth[v] = depth[u] + 1;
dfs1(v);
ft[u] = ft[v];
}
}
bool insubt(int u, int v)
{
//is v in the subtree of u?
if (u == N) return true;
return (st[u] <= st[v] && st[v] <= ft[u]);
}
int lca(int u, int v)
{
//where does v need to go to?
if (insubt(v, u)) return N;
FORD(i, 20, 0)
{
if (insubt(ancestor[i][v], u))
{
continue;
}
v = ancestor[i][v];
}
return v;
}
void go(int u, int v)
{
cerr << "go " << u << ' ' << v << endl;
int w = lca(u, v);
if (w != N)
{
int x = v, diff = depth[v] - depth[w] + 1;
FORD(i, 20, 0)
{
if (diff & (1 << i))
{
// cerr << "L " << i << ' ' << x << endl;
ups[i][x] = -1;
x = ancestor[i][x];
}
}
}
w = lca(v, u);
if (w != N)
{
int x = u, diff = depth[u] - depth[w] + 1;
FORD(i, 20, 0)
{
if (diff & (1 << i))
{
// cerr << "W " << i << ' ' << x << endl;
ups[i][x] = 1;
x = ancestor[i][x];
}
}
}
//update everything on the path u -> v to be in that direction!
}
int32_t main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
// cout << fixed << setprecision(10);
// cerr << fixed << setprecision(10);
// if (fopen("file.in", "r"))
// {
// freopen ("file.in", "r", stdin);
// freopen ("file.out", "w", stdout);
// }
cin >> N >> M;
FOR(i, 0, M)
{
ans[i] = -1;
}
FOR(i, 0, N)
{
dsu[i] = i;
}
FOR(i, 0, M)
{
int u, v;
cin >> u >> v;
u--; v--;
if (u == v)
{
continue;
}
edge[u].PB(v);
edge[v].PB(u);
dup[u][v].PB(i + 1);
dup[v][u].PB(-i - 1);
}
FOR(i, 0, N)
{
sort(ALL(edge[i]));
edge[i].erase(unique(ALL(edge[i])), edge[i].end());
}
cin >> K;
FOR(i, 0, K)
{
int u, v;
cin >> u >> v;
u--; v--;
if (u == v) continue;
needs.PB({u, v});
}
K = 0;
FOR(i, 0, N)
{
if (!seen[i])
{
dfs(i, 1);
}
}
FOR(u, 0, N)
{
for (int v : edge[u])
{
if (!bridge[u][v])
{
merge(u, v);
}
}
}
FOR(u, 0, N)
{
for (int v : edge[u])
{
if (bridge[u][v])
{
edge1[get(u)].PB(get(v));
}
}
}
// FOR(i, 0, N)
// {
// cerr << i << ":";
// for (int v : edge1[i])
// {
// cerr << ' ' << v;
// }
// cerr << endl;
// }
FOR(i, 0, N)
{
parent[i] = N;
}
T = 0;
FOR(i, 0, N)
{
if (get(i) == i && parent[i] == N)
{
dfs1(i);
}
}
FOR(i, 0, N)
{
ancestor[0][i] = parent[i];
// cerr << parent[i] << ' ';
}
// cerr << endl;
FOR(i, 0, 21)
{
ancestor[i][N] = N;
}
FOR(i, 1, 21)
{
FOR(j, 0, N)
{
ancestor[i][j] = ancestor[i - 1][ancestor[i - 1][j]];
}
}
for (pii p : needs)
{
int u = get(p.fi), v = get(p.se);
if (u == v) continue;
go(u, v);
// cerr << "go " << u << ' ' << v << endl;
}
FORD(i, 20, 1)
{
FOR(j, 0, N)
{
if (ups[i][j])
{
ups[i - 1][j] = ups[i][j];
ups[i - 1][ancestor[i - 1][j]] = ups[i][j];
}
}
}
FOR(i, 0, N)
{
res[i] = -1;
if (ups[0][i] == -1)
{
res[i] = 0;
}
if (ups[0][i] == 1)
{
res[i] = 1;
}
cerr << res[i] << endl;
}
FOR(i, 0, N)
{
for (auto p : dup[i])
{
if (SZ(p.se) > 1) continue;
int u = get(i), v = get(p.fi), ed = p.se[0];
if (ed < 0) continue;
ed--;
if (u == v) continue;
// cerr << u << " -> " << v << endl;
if (parent[v] == u)
{
ans[ed] = (res[v] == -1 ? -1 : res[v]);
}
else
{
ans[ed] = (res[u] == -1 ? -1 : res[u] ^ 1);
}
}
}
FOR(i, 0, M)
{
if (ans[i] == -1)
{
cout << 'B';
}
if (ans[i] == 0)
{
cout << 'R';
}
if (ans[i] == 1)
{
cout << 'L';
}
}
cout << '\n';
// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
return 0;
}
/* READ READ READ
* int overflow, maxn too small, special cases (n=1?, two distinct?), cin.tie() interactive
* reread the problem, try small cases
* note down possible sources of error as you go
* do smth instead of nothing
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
100 ms |
92972 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
100 ms |
92972 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
100 ms |
92972 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
