Submission #384912

#	Time	Username	Problem	Language	Result	Execution time	Memory
384912		codebuster_10	Pipes (CEOI15_pipes)	C++17	10 / 100	266 ms	22124 KiB

pipes

#include <bits/stdc++.h>

using namespace std ;

//#define int int64_t //be careful about this 
#define endl "\n"
#define f(i,a,b) for(int i=int(a);i<int(b);++i)

#define pr pair
#define ar array
#define fr first
#define sc second
#define vt vector
#define pb push_back
#define LB lower_bound  
#define UB upper_bound
#define PQ priority_queue

#define sz(x) ((int)(x).size())
#define all(a) (a).begin(),(a).end()
#define allr(a) (a).rbegin(),(a).rend()
#define mem0(a) memset(a, 0, sizeof(a))
#define mem1(a) memset(a, -1, sizeof(a))

template<class A> void rd(vt<A>& v);
template<class T> void rd(T& x){ cin >> x; }
template<class H, class... T> void rd(H& h, T&... t) { rd(h) ; rd(t...) ;}
template<class A> void rd(vt<A>& x) { for(auto& a : x) rd(a) ;}

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

template<typename T>
void __p(T a) {
  cout<<a; 
}
template<typename T, typename F>
void __p(pair<T, F> a) {
  cout<<"{";
  __p(a.first);
  cout<<",";
  __p(a.second);
  cout<<"}\n"; 
}
template<typename T>
void __p(std::vector<T> a) {
  cout<<"{";
  for(auto it=a.begin(); it<a.end(); it++)
    __p(*it),cout<<",}\n"[it+1==a.end()]; 
}
template<typename T, typename ...Arg>
void __p(T a1, Arg ...a) {
  __p(a1);
  __p(a...);
}
template<typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
  cout<<name<<" : ";
  __p(arg1);
  cout<<endl;
}
template<typename Arg1, typename ... Args>
void __f(const char *names, Arg1 &&arg1, Args &&... args) {
  int bracket=0,i=0;
  for(;; i++)
    if(names[i]==','&&bracket==0)
      break;
    else if(names[i]=='(')
      bracket++;
    else if(names[i]==')')
      bracket--;
  const char *comma=names+i;
  cout.write(names,comma-names)<<" : ";
  __p(arg1);
  cout<<" | ";
  __f(comma+1,args...);
}

void setIO(string s = "") {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); 
  cin.exceptions(cin.failbit); 
	cout.precision(15);	cout << fixed;
  #ifdef ONLINE_JUDGE
  if(sz(s)){
  	freopen((s+".in").c_str(),"r",stdin);
  	freopen((s+".out").c_str(),"w",stdout);
  }
  #endif
}
/*
	*Description :- following gives bridges in a graph.
	*Graph may not be connected but graph should be simple for this to work
	*Complexity :- O(E+V);
	*Verification :- https://judge.yosupo.jp/submission/43660
*/
const int MAX_N = 1e4;
vt<int> g[MAX_N], d(MAX_N,0), par(MAX_N,-1),up(MAX_N,0), down(MAX_N,0), dp(MAX_N);
vt<bool> vis(MAX_N,false);
vt<pr<int,int>> get_bridges(int root){
	vt<int> nodes;
	vt<pr<int,int>> ans;
	function<void(int)> dfs=[&](int i){
		for(auto j : g[i]) if(!vis[j]){
			par[j] = i ;
			d[j] = d[i] + 1;
			vis[j] = 1;
			nodes.pb(j); 
			dfs(j);
		}
	};
	vis[root] = true;
	d[root] = 0 ;
	nodes.pb(root);
	dfs(root);
	for(auto i : nodes){
		for(auto j : g[i]){
			if(d[j] > d[i]){
				if(d[j] - d[i] > 1) down[i]++;
			}else if(d[j] < d[i]){
				if(d[i] - d[j] > 1) up[i]++;
			}else{
				assert(false);
			}
		}
		vis[i] = false ;
	}
	function<void(int)> dfs2=[&](int i){
		dp[i] = up[i] - down[i];
		for(auto j : g[i]) if(!vis[j]){
			vis[j] = 1; dfs2(j);
			dp[i] += dp[j];
		}
		if(i != root && dp[i] == 0){
			ans.pb({par[i],i});
		}
	};
	vis[root] = true;
	dfs2(root);
	return ans;
}
signed main(){
  setIO() ;
  int n,m; rd(n,m);
  while(m--){
  	int u,v; rd(u,v); --u,--v;
  	g[u].pb(v); g[v].pb(u);
  }
  f(i,0,n){
  	if(!vis[i]){
  		auto ans = get_bridges(i);
  		for(auto e : ans){
  			cout << e.fr + 1 << ' ' << e.sc + 1 << endl ;
  		}
  	}
  }
  
}

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• Subtask 3: 10 / 10
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