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beautifulgraph.cpp
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beautifulgraph.cpp
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#include<iostream>
#include<vector>
#include<math.h>
#include<bits/stdc++.h>
#define lli long long int
#define mod 998244353
#define pb push_back
using namespace std;
vector<lli> ar[1000000];
lli vis[1000000],col[1000000],c[2];
//in bipartite graph every vertex(node) must lies in only on set and if there is edge between two nodes of different sets then there must be a edge joining them
// and there is no edge between two nodes of the same set
bool DFS(lli s,lli cl)
{
vis[s]=1;
col[s]=cl;
c[cl]++;
for(lli child : ar[s])
{
if((vis[child]==0 && DFS(child,cl^1)==false) || col[child]==col[s])
return false;
}
return true;
}
lli power(lli a,lli n)
{
lli p=1;
while(n)
{
if(n&1)
p=(p*a)%mod;
a=(a*a)%mod;
n>>=1;
}
return p;
}
int main()
{
ios_base::sync_with_stdio(false);
cout.tie(NULL);
int t;
cin>>t;
while(t--)
{
lli n,m,a,b,i,ans=1,f=0;
cin>>n>>m;
for(i=1;i<=n;i++)
ar[i].clear(), vis[i]=0;
for(i=0;i<m;i++)
cin>>a>>b, ar[a].pb(b) , ar[b].pb(a);
for(i=1;i<=n;i++)
{
if(vis[i]==0)
{
c[0]=c[1]=0;
if(DFS(i,0)==false)
{
f=1;
break;
}
ans=(ans*(power(2,c[0])+power(2,c[1])))%mod ;
}
}
if(f)
cout<<0<<endl;
else
cout<<ans<<endl;
}
return 0;
}