/// slava sovet·skomu soyuzu
#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define ll long long
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
const ll mod = 1e9 + 7;
const int maxN = 2000005;
int n,m,p;
int x[maxN],y[maxN];
vector<pii> adj1[maxN];
map<pii,int> apr;
char res[maxN];
int isbridge[maxN];
void read()
{
cin >> n >> m;
for(int i = 1; i <= m; i++)
{
cin >> x[i] >> y[i];
res[i] = 'B';
if(x[i] == y[i])
{
continue;
}
if(apr[make_pair(min(x[i],y[i]),max(x[i],y[i]))] == 0)
{
adj1[x[i]].push_back({y[i],i});
adj1[y[i]].push_back({x[i],i});
}
apr[make_pair(min(x[i],y[i]),max(x[i],y[i]))]++;
}
}
int num[maxN],low[maxN];
int TimeDFS = 0;
void preDFS(int u,int pre)
{
num[u] = low[u] = ++TimeDFS;
for(pii x : adj1[u])
{
if(x.fi == pre) continue;
if(!num[x.fi])
{
preDFS(x.fi,u);
low[u] = min(low[u],low[x.fi]);
if(low[x.fi] == num[x.fi] && apr[ {min(u,x.fi),max(u,x.fi)}] == 1)
{
isbridge[x.se] = 1;
}
}
else
{
low[u] = min(low[u],num[x.fi]);
}
}
}
int isvis[maxN];
int cnt_grp = 0;
vector<vector<int>> adj2[maxN];
int grp[maxN];
void DFS_Build(int u)
{
isvis[u] = 1;
for(pii t : adj1[u])
{
if(isvis[t.fi]) continue;
if(isbridge[t.se])
{
cnt_grp++;
grp[t.fi] = cnt_grp;
if(u == x[t.se])
{
adj2[grp[u]].push_back({grp[t.fi],t.se,1});
adj2[grp[t.fi]].push_back({grp[u],t.se,0});
}
else
{
adj2[grp[u]].push_back({grp[t.fi],t.se,0});
adj2[grp[t.fi]].push_back({grp[u],t.se,1});
}
}
else grp[t.fi] = grp[u];
DFS_Build(t.fi);
}
}
int save_e[maxN];
int anc[25][maxN];
int dp[maxN];
int depth[maxN];
void DFS2(int u,int p)
{
for(vector<int> x : adj2[u])
{
int v = x[0];
if(v == p) continue;
depth[v] = depth[u] + 1;
save_e[v] = x[1];
if(x[2] == 1)
{
res[x[1]] = 'R';
}
else res[x[1]] = 'L';
anc[0][v] = u;
for(int i = 1; i <= (int)log2(n); i++)
{
anc[i][v] = anc[i-1][anc[i-1][v]];
}
DFS2(v,u);
}
}
void DFS3(int u,int p)
{
for(vector<int> x : adj2[u])
{
int v = x[0];
if(v == p) continue;
DFS3(v,u);
dp[u] += dp[v];
}
}
int LCA(int u,int v)
{
if(depth[u] < depth[v]) swap(u,v);
int k = depth[u] - depth[v];
for(int i = (int)log2(n); i >= 0; i--)
{
if(k & (1 << i))
{
u = anc[i][u];
}
}
if(u == v) return u;
for(int i = (int)log2(n); i >= 0; i--)
{
if(anc[i][u] != anc[i][v])
{
u = anc[i][u];
v = anc[i][v];
}
}
return anc[0][u];
}
void sol()
{
for(int i = 1; i <= n; i++)
{
if(!num[i])
{
preDFS(i,i);
}
}
for(int i = 1; i <= n; i++)
{
if(!isvis[i])
{
cnt_grp++;
grp[i] = cnt_grp;
DFS_Build(i);
}
}
/*for(int i = 1; i <= n; i++)
{
cout << grp[i] <<' ';
}
cout <<'\n'<<"dark";
return;*/
for(int i = 1; i <= cnt_grp; i++)
{
if(depth[i] == 0) DFS2(i,i);
}
cin >> p;
while(p--)
{
int a,b;
cin >> a >> b;
dp[LCA(grp[a],grp[b])]--;
dp[grp[a]]++;
}
//cout << save_e[2];return;
for(int i = 1; i <= cnt_grp; i++)
{
if(depth[i] == 0) DFS3(i,i);
}
for(int i = 1; i <= cnt_grp; i++)
{
if(depth[i] == 0)
{
continue;
}
if(dp[i] > 0)
{
res[save_e[i]] = 'L' + 'R' - res[save_e[i]];
}
}
for(int i = 1; i <= m; i++)
{
cout << res[i];
}
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tests;
//cin >> tests;
tests = 1;
while (tests--)
{
read();
sol();
}
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
48 ms |
94280 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
48 ms |
94280 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
48 ms |
94280 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
