553C - Love Triangles - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
vector <int> a[100001],c[100001];
int d[100001],n,m,u,v,k,kq,f[100001];
const int mod=round(1e9)+7;
void DFS(int u,int p)
{
    d[u]=1;
    for(int i=0;i<a[u].size();i++)
    {
        int v=a[u][i];
        if(d[v]==0)
        {
            f[v]=f[u]^c[u][i];
            DFS(v,u);
        }
        else if((f[v]^f[u]^c[u][i])==1) { cout<<0; exit(0); }
    }
}
int main()
{
    //freopen("ntu.inp","r",stdin);
    //freopen("ntu.out","w",stdout);
    cin>>n>>m;
    while(m--)
    {
        cin>>u>>v>>k; k=1-k;
        a[u].push_back(v); a[v].push_back(u);
        c[u].push_back(k); c[v].push_back(k);
    }
    for(u=1;u<=n;u++)
        if(d[u]==0)
        {
            DFS(u,0);
            if(kq==0) kq=1; else kq=kq*2%mod;
        }
    cout<<kq;
}