multisource Breadth-First Search code example

Example: multisource bfs c++

//just push all the sources into the queue and perform simple bfs
vector<int> sources;

unordered_map<int,bool> vis;
unordered_map<int,int> dist;
queue<int> q;

for(int i = 0;i<sources.size();i++){
            vis[sources[i]] = true;
            dist[sources[i]] = 0;
            q.push(sources[i]);
}
// then proceed as usual


while(!q.empty()){
  int p = q.front();
  q.pop();

  for(int i = 0;i< g[p].size();i++){
    if(!vis[g[p][i]]){
      vis[g[p][i]] = true;
      dist[g[p][i]] = dist[p] + 1;
      q.push(g[p][i]);
    }
  }
}