//thatsramen
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define eb emplace_back
#define pb push_back
#define ft first
#define sd second
#define pi pair<int, int>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define dbg(...) dbg_out(__VA_ARGS__)
using ll = long long;
using ld = long double;
using namespace std;
using namespace __gnu_pbds;
//Constants
const ll INF = 5 * 1e18;
const int IINF = 2 * 1e9;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const ld PI = 3.14159265359;
//Templates
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) {return os << '(' << p.first << ", " << p.second << ')';}
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) {os << '['; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << ']';}
void dbg_out() {cerr << endl;}
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << H << ' '; dbg_out(T...); }
template<typename T> void mins(T& x, T y) {x = min(x, y);}
template<typename T> void maxs(T& x, T y) {x = max(x, y);}
template<typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using omset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
//order_of_key(k): number of elements strictly less than k
//find_by_order(k): k-th element in the set
void setPrec() {cout << fixed << setprecision(15);}
void unsyncIO() {cin.tie(0)->sync_with_stdio(0);}
void setIn(string s) {freopen(s.c_str(), "r", stdin);}
void setOut(string s) {freopen(s.c_str(), "w", stdout);}
void setIO(string s = "") {
unsyncIO(); setPrec();
if(s.size()) setIn(s + ".in"), setOut(s + ".out");
}
// #define TEST_CASES
void solve() {
int n, m;
cin >> n >> m;
vector<vector<pi>> e(n + 5);
vector<pi> edges;
for (int i = 1; i <= m; i++) {
int u, v; cin >> u >> v;
e[u].pb({v, i});
e[v].pb({u, i});
edges.pb({u, v});
}
int q; cin >> q;
vector<pi> need(q);
for (int i = 0; i < q; i++) {
cin >> need[i].ft >> need[i].sd;
}
vector<bool> isBridge(m + 5, false);
vector<char> ans(m + 5, 'B');
vector<int> comp(n + 5);
{
vector<bool> vis(n + 5, false);
vector<int> dp(n + 5, IINF), dep(n + 5, 0);
function<void(int, int)> find_bridges = [&](int f, int p) {
vis[f] = true;
dp[f] = dep[f];
for (pi to : e[f]) {
if (to.ft == p) continue;
if (!vis[to.ft]) {
dep[to.ft] = dep[f] + 1;
find_bridges(to.ft, f);
if (dp[to.ft] > dep[f]) {
// bridge found, yay!
isBridge[to.sd] = true;
}
mins(dp[f], dp[to.ft]);
} else mins(dp[f], dep[to.ft]);
}
};
function<void(int, int)> color_component = [&](int f, int cc) {
vis[f] = true; comp[f] = cc;
for (pi to : e[f]) {
if (!vis[to.ft])
if (!isBridge[to.sd])
color_component(to.ft, cc);
}
};
for (int i = 1; i <= n; i++) {
if (!vis[i])
find_bridges(i, -1);
}
fill(all(vis), false);
for (int i = 1, pp = 1; i <= n; i++) {
if (!vis[i])
color_component(i, pp++);
}
}
{
vector<vector<pi>> e_comp(n + 5);
for (int i = 1; i <= m; i++) {
if (isBridge[i]) {
int u = comp[edges[i - 1].ft], v = comp[edges[i - 1].sd];
e_comp[u].pb({v, i}); e_comp[v].pb({u, -i});
}
}
int LOG = 17;
vector<vector<int>> jump(n + 5, vector<int> (LOG + 5, -1));
vector<int> val(n + 5, 0), dep(n + 5, 0); vector<int> dir(n + 5, 0);
function<void(int, int)> dfs1 = [&](int f, int p) {
jump[f][0] = p;
for (int i = 1; i <= LOG; i++)
jump[f][i] = jump[jump[f][i - 1]][i - 1];
for (pi to : e_comp[f]) {
if (to.ft != p && to.ft != f) {
dep[to.ft] = dep[f] + 1;
dfs1(to.ft, f);
}
}
};
for (int i = 1; i <= n; i++) {
if (jump[i][0] == -1)
dfs1(i, i);
}
auto get = [&](int u, int v) -> int {
if (dep[u] < dep[v]) swap(u, v);
for (int i = LOG; i >= 0; i--) {
int to = jump[u][i];
if (dep[to] >= dep[v]) u = to;
}
if (u == v) return u;
for (int i = LOG; i >= 0; i--) {
int uu = jump[u][i], vv = jump[v][i];
if (uu != vv) {
u = uu; v = vv;
}
}
return jump[u][0];
};
for (pi x : need) {
int u = comp[x.ft], v = comp[x.sd];
int lca = get(u, v);
val[lca] -= 2;
val[u]++; val[v]++;
dir[u] = 1; dir[v] = -1;
}
vector<bool> vis(n + 5, false);
vector<int> dp(n + 5, 0);
function<void(int)> dfs2 = [&](int f) {
vis[f] = true;
dp[f] = val[f];
for (pi to : e_comp[f]) {
if (!vis[to.ft]) {
dfs2(to.ft);
if (dp[to.ft] > 0) {
dir[f] = dir[to.ft];
if ((dir[to.ft] > 0 && to.sd < 0) || (dir[to.ft] < 0 && to.sd > 0)) {
ans[(to.sd > 0 ? 1 : -1) * to.sd] = 'R';
} else {
ans[(to.sd > 0 ? 1 : -1) * to.sd] = 'L';
}
}
dp[f] += dp[to.ft];
}
}
};
for (int i = 1; i <= n; i++) {
if (!vis[i])
dfs2(i);
}
}
for (int i = 1; i <= m; i++) {
cout << ans[i];
}
}
int main() {
setIO();
int tt = 1;
#ifdef TEST_CASES
cin >> tt;
#endif
while (tt--)
solve();
return 0;
}
Compilation message
oneway.cpp: In function 'void setIn(std::string)':
oneway.cpp:44:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
44 | void setIn(string s) {freopen(s.c_str(), "r", stdin);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp: In function 'void setOut(std::string)':
oneway.cpp:45:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
45 | void setOut(string s) {freopen(s.c_str(), "w", stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
468 KB |
Output is correct |
| 4 |
Incorrect |
1 ms |
468 KB |
Output isn't correct |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
468 KB |
Output is correct |
| 4 |
Incorrect |
1 ms |
468 KB |
Output isn't correct |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
468 KB |
Output is correct |
| 4 |
Incorrect |
1 ms |
468 KB |
Output isn't correct |
| 5 |
Halted |
0 ms |
0 KB |
- |
