#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
//#pragma GCC optimize("Ofast") //#pragma GCC optimize "unroll-loops" //#pragma GCC target "sse,sse2,sse3,sse4,abm,avx,avx2,fma,mmx,popcnt,tune=native" //#pragma GCC optimize "prefetch-loop-arrays"
using namespace std; using namespace __gnu_pbds;
#define foru(i,a,b) for(int i=(a);i<(b);i++)
#define ford(i,a,b) for(int i=(a);i>=(b);i--)
#define fori(a,b) foru(i,a,b)
#define forj(a,b) foru(j,a,b)
#define fork(a,b) foru(k,a,b)
#define seto(x,i) memset(x,i,sizeof x)
#define pf first
#define ps second
#define pb push_back
#define eb emplace_back
#define em emplace
#define mp make_pair
#define mt make_tuple
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define clz __builtin_clz
#define clzll __builtin_clzll
#define ctz __builtin_ctz
#define ctzll __builtin_ctzll
#define P2(x) (1LL<<(x))
#define sz(x) (int)x.size()
#define all(x) begin(x),end(x)
#if __SIZEOF_INT128__
typedef __int128_t i128; typedef __uint128_t ui128;
#else
typedef int64_t i128; typedef uint64_t ui128;
#endif
typedef int64_t ll; typedef uint64_t ull; typedef long double lld;
typedef pair<int,int> pii; typedef pair<ll,ll> pll; typedef pair<lld,lld> pdd;
template<class T1,class T2> using ordered_map=tree<T1,T2,less<T1>,rb_tree_tag,tree_order_statistics_node_update>; template<class T1> using ordered_set=ordered_map<T1,null_type>;
template<class T> using minpq=std::priority_queue<T,vector<T>,greater<T>>; template<class T> using maxpq=std::priority_queue<T,vector<T>,less<T>>;
template<class T> using minpairingheap=__gnu_pbds::priority_queue<T,greater<T>,pairing_heap_tag>; template<class T>using maxpairingheap=__gnu_pbds::priority_queue<T,less<T>,pairing_heap_tag>;
const int inf=0x3f3f3f3f,MOD=1e9+7; const ll INF=0x3f3f3f3f3f3f3f3f; const lld PI=acos((lld)-1);
const ll SEED=443214^chrono::duration_cast<chrono::nanoseconds>(chrono::high_resolution_clock::now().time_since_epoch()).count();
mt19937 randgen(SEED); ll rand(ll a, ll b){return uniform_int_distribution<ll>(a,b)(randgen);}
ll gcd(ll a, ll b){return b?gcd(b,a%b):a;}
ll fpow(ll a,ll b){ll ret=1;for(;b;b>>=1){if(b&1) ret=ret*a%MOD;a=a*a%MOD;}return ret;} ll fpow(ll a,ll b,ll M){ll ret=1;for(;b;b>>=1){if(b&1) ret=ret*a%M;a=a*a%M;}return ret;}
template<class T1,class T2>constexpr const auto _min(const T1&x,const T2&y){return x<y?x:y;} template<class T,class...Ts>constexpr auto _min(const T&x,const Ts&...xs){return _min(x,_min(xs...));}
template<class T1,class T2>constexpr const auto _max(const T1&x,const T2&y){return x>y?x:y;} template<class T,class...Ts>constexpr auto _max(const T&x,const Ts&...xs){return _max(x,_max(xs...));}
#define min(...) _min(__VA_ARGS__)
#define max(...) _max(__VA_ARGS__)
template<class T1,class T2>constexpr bool ckmin(T1&x,const T2&y){return x>y?x=y,1:0;} template<class T,class...Ts>constexpr bool ckmin(T&x,const Ts&...xs){return ckmin(x,min(xs...));}
template<class T1,class T2>constexpr bool ckmax(T1&x,const T2&y){return x<y?x=y,1:0;} template<class T,class...Ts>constexpr bool ckmax(T&x,const Ts&...xs){return ckmax(x,max(xs...));}
struct chash{
static ll splitmix64(ll x){x+=0x9e3779b97f4a7c15; x=(x^(x>>30))*0xbf58476d1ce4e5b9; x=(x^(x>>27))*0x94d049bb133111eb; return x^(x>>31);}
template<class T> size_t operator()(const T &x) const{return splitmix64(hash<T>()(x)+SEED);}
template<class T1,class T2> size_t operator()(const pair<T1,T2>&x)const{return 31*operator()(x.first)+operator()(x.second);}};
void fIn(string s){freopen(s.c_str(),"r",stdin);} void fOut(string s){freopen(s.c_str(),"w",stdout);} void fIO(string s){fIn(s+".in"); fOut(s+".out");}
string to_string(char c){return string(1,c);} string to_string(char* s){return (string)s;} string to_string(string s){return s;}
template<class T> string to_string(complex<T> c){stringstream ss; ss<<c; return ss.str();}
template<class T1,class T2> string to_string(pair<T1,T2> p){return "("+to_string(p.pf)+","+to_string(p.ps)+")";}
template<class T> string to_string(T v){string ret="{"; for(const auto& x:v) ret+=to_string(x)+","; return ret+"}";}
void DBG(){cerr<<"]"<<endl;} template<class T,class... Ts> void DBG(T x,Ts... xs){cerr<<to_string(x); if(sizeof...(xs)) cerr<<", "; DBG(xs...);}
#ifdef LOCAL
#define dbg(...) cerr<<"Line("<< __LINE__<<") -> ["<<#__VA_ARGS__<<"]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif
#define nl "\n"
const int N=100010,M=MOD;
int n,m,a,b;
vector<int> gr[N];
struct BCC{
int n2,dfn[N],low[N],inx;
BCC(){
n2=0; inx=0; seto(dfn,0);
}
void genBCC(int v,int p=0){ // bridge bcc
bool pp=0;
low[v]=dfn[v]=++inx;
for(auto i:gr[v]) if(i!=p&&!pp){
if(dfn[i]) ckmin(low[v],dfn[i]); //works with min(low[v],low[i])
else{
genBCC(i,v);
ckmin(low[v],low[i]);
}
}
else pp=1;
if(low[v]==dfn[v]&&p) cout<<v<<" "<<p<<nl;
}
}bcc;
struct DSU{
int p[N];
DSU(){seto(p,-1);}
int head(int x){return p[x]<0? x: p[x]=head(p[x]);}
bool link(int x,int y){
x=head(x); y=head(y);
if(x==y) return 0;
if(p[x]>p[y]) swap(x,y);
p[x]+=p[y]; p[y]=x;
return 1;
}
}d1,d2;
vector<pii> e;
int main(){
cin.tie(0)->sync_with_stdio(0);
cin>>n>>m;
fori(0,m){
cin>>a>>b;
if(d1.link(a,b)||d2.link(a,b)) e.eb(a,b);
}
//dbg(e);
for(auto [a,b]:e) gr[a].pb(b), gr[b].pb(a);
fori(1,n+1) if(!bcc.dfn[i]) bcc.genBCC(i);
return 0;
}
/**
*/
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:111:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
111 | for(auto [a,b]:e) gr[a].pb(b), gr[b].pb(a);
| ^
pipes.cpp: In function 'void fIn(std::string)':
pipes.cpp:54:27: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
54 | void fIn(string s){freopen(s.c_str(),"r",stdin);} void fOut(string s){freopen(s.c_str(),"w",stdout);} void fIO(string s){fIn(s+".in"); fOut(s+".out");}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
pipes.cpp: In function 'void fOut(std::string)':
pipes.cpp:54:78: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
54 | void fIn(string s){freopen(s.c_str(),"r",stdin);} void fOut(string s){freopen(s.c_str(),"w",stdout);} void fIO(string s){fIn(s+".in"); fOut(s+".out");}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
3 ms |
3820 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
7 ms |
4204 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
104 ms |
4076 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
176 ms |
4464 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
290 ms |
5480 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
398 ms |
8672 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
589 ms |
9312 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
786 ms |
10644 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
963 ms |
10592 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
1159 ms |
10208 KB |
Wrong number of edges |
| 2 |
Halted |
0 ms |
0 KB |
- |
