1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
#include <fstream>
#include <vector>
#include <stack>
#include <set>
#define min(a,b) ( ((a)<(b))?(a):(b) )
#define DIM 100005
using namespace std;
 
ifstream fin("biconex.in");
ofstream fout("biconex.out");
 
int m,n;
vector <int> G[DIM];
set <int> compBiconexe[DIM];
stack < pair<int,int> > mStack;
int h[DIM],returnNode[DIM],timpDescoperire;
int cbx;
 
 
void dfsPct(int u,int parinte)
{
    h[u] = timpDescoperire;
    timpDescoperire++;
    returnNode[u] = h[u];
 
    for(int i=0;i<G[u].size();++i)
    {
        int v = G[u][i];
 
        if(!h[v])
        {
            mStack.push(make_pair(u,v));
            dfsPct(v,u);
            returnNode[u] = min(returnNode[u],returnNode[v]);
 
            if(returnNode[v]>=h[u])
            {
                cbx++;
                pair <int,int> node;
                do
                {
                    node = mStack.top();
                    mStack.pop();
                    compBiconexe[cbx].insert(node.first);
                    compBiconexe[cbx].insert(node.second);
 
                }while((node.first!=u || node.second!=v) && (node.second!=u || node.first!=v));
            }
        }
        else if(v!=parinte) returnNode[u] = min(returnNode[u],h[v]);
    }
 
}
void comp_biconexe()
{
    for(int u=1;u<=n;++u)
        if(!h[u])
        {
            timpDescoperire = 1;
            dfsPct(u,0);
        }
}
 
int main()
{
    int a,b;
    fin>>n>>m;
 
    while(m--)
    {
        fin>>a>>b;
        G[a].push_back(b);
        G[b].push_back(a);
    }
 
    comp_biconexe();
 
    fout<<cbx<<"\n";
 
    for(int i=1;i<=cbx;++i){
        for(set<int>::iterator j=compBiconexe[i].begin();j!=compBiconexe[i].end();++j){
            fout<<*j<<" ";
        }
        fout<<"\n";
    }
 
    return 0;
}