#include<bits/stdc++.h>
using namespace std;
long long n,m;
long long dfn[100001],low[1000001],jl;
long long head[100001],next[100001];
long long jk[100001],ans=1;
long long l;
bool br[100001];

struct bit{
	long long x,y;
}o[100001];

bool cmp(const bit a,const bit b){
	if(a.x==b.x) return a.y<b.y;
	return a.x<b.x;
}

void add(long long x,long long y) {
    jk[++ans]=y,next[ans]=head[x],head[x]=ans;
    return;
}

void Tarjian(long long x,long long k)
{
	dfn[x]=low[x]=++jl;
	for(long long i=head[x];i;i=next[i]){
		long long y=jk[i];
		if(!dfn[y]){
			Tarjian(y,i);
			low[x]=min(low[x],low[y]);
			if(low[y]>dfn[x]) br[i]=br[i^1]=1;
		}
		else if(i!=(k^1)) low[x]=min(low[x],dfn[y]);
			
	}
	return;
}

int main()
{
    std::cin.tie(0);
    std::cout.tie(0);
    cin>>n>>m;
    for(long long i=1;i<=m;i++){
    	long long x,y;
    	cin>>x>>y;
    	add(x,y);//单向边 
    	add(y,x);//双向边 
	}
	for(long long i=1;i<=n;i++)
		if(!dfn[i]) Tarjian(i,0);
	for(long long i=2;i<=ans;i++){
		if(br[i]==1){
			l++;
			o[l].x=min(jk[i^1],jk[i]);
			o[l].y=max(jk[i^1],jk[i]);
		} 
	}
	std::sort(o+1,o+l+1,cmp);
	for(long long i=1;i<=l;i++){
		if(o[i].x==o[i+1].x){
			if(o[i].y==o[i+1].y){
				continue;
			}
			else cout<<o[i].x<<" "<<o[i].y<<"\n"; 
		}
		else cout<<o[i].x<<" "<<o[i].y<<"\n"; 
	}
		
    return 0;
} 

luogu编译失败原因：

/tmp/compiler_zwwyetrp/src: 在函数‘void add(long long int, long long int)’中:

/tmp/compiler_zwwyetrp/src:20:17: 错误：对‘next’的引用有歧义
   20 |   
   
   jk[++ans]=y,next[ans]=head[x],head[x]=ans;
      |                 ^~~~
In file included from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/stl_algobase.h:66,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/char_traits.h:39,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/ios:40,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/istream:38,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/sstream:38,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/complex:45,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/ccomplex:39,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/x86_64-unknown-linux-gnu/bits/stdc++.h:54,
                 from /tmp/compiler_zwwyetrp/src:1:
/nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/stl_iterator_base_funcs.h:213:5: 附注：备选为： ‘template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)’
  213 |     next(_InputIterator __x, typename
      |     ^~~~
/tmp/compiler_zwwyetrp/src:5:24: 附注：         ‘long long int next [100001]’
    5 | long long head[100001],next[100001];
      |                        ^~~~
/tmp/compiler_zwwyetrp/src: 在函数‘void Tarjian(long long int, long long int)’中:
/tmp/compiler_zwwyetrp/src:27:30: 错误：对‘next’的引用有歧义
   27 |  for(long long i=head[x];i;i=next[i]){
      |                              ^~~~
In file included from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/stl_algobase.h:66,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/char_traits.h:39,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/ios:40,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/istream:38,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/sstream:38,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/complex:45,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/ccomplex:39,
                 from /nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/x86_64-unknown-linux-gnu/bits/stdc++.h:54,
                 from /tmp/compiler_zwwyetrp/src:1:
/nix/store/bbmwawbq7wjb54fa35wr72alcm083d1f-luogu-gcc-9.3.0/include/c++/9.3.0/bits/stl_iterator_base_funcs.h:213:5: 附注：备选为： ‘template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)’
  213 |     next(_InputIterator __x, typename
      |     ^~~~
   
/tmp/compiler_zwwyetrp/src:5:24: 附注：         ‘long long int next [100001]’
    5 | long long head[100001],next[100001];
      |                        ^~~~