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Articulation_bridge.cpp
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Articulation_bridge.cpp
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#include<bits/stdc++.h>
#define pf printf
#define sc scanf
#define PI 2*acos(0.0)
#define fast ios_base::sync_with_stdio(false);cin.tie(0); cout.tie(0)
#define mem(a,b) memset(a, b, sizeof(a) )
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (a*(b/gcd(a,b)))
#define MAX 1234567899
#define mod 1000000007
#define all(v) (v).begin(),(v).end()
#define vSort(v) sort(all(v))
#define maxSort(v) sort(all(v),greater<int>())
#define Unique(v) v.erase(unique(all(v)),v.end())
#define sqr(x) ((x)*(x))
#define qube(x) ((x)*(x)*(x))
#define deci(n) cout<<fixed<<setprecision(n)
#define sci(n) sc("%d",&(n))
#define scii(x,y) sc("%d %d",&(x),&(y))
#define scl(x) sc("%lld",&(x))
#define scll(x,y) sc("%lld %lld",&(x),&(y))
#define vi vector<int>
#define hi pf(" HI \n")
#define pp pair<int,int>
#define pb(x) push_back(x)
#define mp(x,y) make_pair(x,y)
#define F first
#define S second
#define check(n,pos) (n & (1<<(pos)))
#define biton(n,pos) (n (1<<(pos)))
#define bitoff(n,pos) (n & ~(1<<(pos)))
typedef long long int lli;
typedef unsigned long long int ulli;
int dx4[] = { 0, 0, -1, 1 } ;
int dy4[] = { -1, 1, 0, 0 } ;
bool valid( int r, int c, int x, int y )
{
if( x >= 1 && x <= r && y >= 1 && y <= c ) return 1 ;
return 0 ;
}
using namespace std;
vi graph[200005];
int vis[200005];
int start[200005];
int par[200005];
int low[200005];
int val=0;
vector<pp> vec;
void tarjan(int u)
{
vis[u]=1;
val++;
start[u]=val;
low[u]=val;
for(int i=0; i<graph[u].size(); i++)
{
int v = graph[u][i];
if(par[u]==v)
continue;
if(vis[v]==0)
{
par[v]=u;
tarjan(v);
low[u] = min(low[u],low[v]);
if(low[v]>start[u])
{
int x = u;
int y = v;
if(x>y)
swap(x,y);
vec.pb(mp(x,y));
}
}
else
{
low[u] = min(low[u],start[v]);
}
}
}
void Articulation_bridge(int node)
{
for(int i=1; i<=node; i++)
par[i] = -1;
for(int i=1; i<=node; i++)
{
if(vis[i]==0)
{
tarjan(i);
}
}
}
int main ()
{
int t;
cin >> t;
for(int cs=1; cs<=t; cs++)
{
int node,edge;
cin>> node >> edge;
int u,v;
for(int i=1; i<=edge; i++)
{
cin >> u >> v;
graph[u].pb(v);
graph[v].pb(u);
}
Articulation_bridge(node);
cout <<"Case "<<cs <<":"<<endl;
vSort(vec);
Unique(vec);
cout << vec.size()<< " critical links"<<endl;
for(int j=0;j<vec.size();j++)
cout << vec[j].F << " - "<<vec[j].S<< endl;
for(int i=0; i<=node; i++)
{
vis[i]=0;
graph[i].clear();
start[i]=1;
}
vec.clear();
}
return 0;
}