# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1026968 | vjudge1 | Pipes (CEOI15_pipes) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 1e5;
vector < int > adj[N + 2];
struct dsu{
int par[N + 2];
int find_par(int &u){
if(par[u] < 0)return u;
par[u] = find_par(par[u]);
return par[u];
}
bool union_set(int u , int v){
u = find_par(u);
v = find_par(v);
if(u != v){
if(par[u] > par[v])swap(u , v);
par[u] += par[v];
par[v] = u;
return true;
}
return false;
}
} par1 , par2;
int timer = 0;
void dfs(int &u , int &p){
par1.par[u] = par2.par[u] = ++timer;
for(int v:adj[u]){
if(v == p) continue;
if(!par2.par[v]){
dfs(v , u);
par1.par[u] = min(par1.par[u] , par1.par[v]);
if(par1.par[v] == par2.par[v]) cout << u << " " << v <<'\n';
}
else par1.par[u] = min(par1.par[u] , par2.par[v]);
}
}
void solve() {
int n , m;
cin >> n >> m;
memset(par1.par , -1 , sizeof(par1.par));
memset(par2.par , -1 , sizeof(par2.par));
for(int i = 1; i <= m ;i ++){
int u , v;
cin >> u >> v;
if(par1.union_set(u , v)){
adj[u].push_back(v);
adj[v].push_back(u);
}
else if(par2.union_set(u , v)){
adj[u].push_back(v);
adj[v].push_back(u);
}
}
memset(par1.par , 0 , sizeof(par1.par));
memset(par2.par , 0 , sizeof(par2.par));
for(int i = 1; i <= n ; i++){
if(!par2.par[i])dfs(i , 0);
}
}
signed main() {
ios::sync_with_stdio(0), cin.tie(0);
#define _ "maxseq."
if (fopen(_ "inp", "r")) {
freopen(_ "inp", "r", stdin);
freopen(_ "out", "w", stdout);
}
solve();
}