DFS.cpp

>> DFS 
                        
        >>> Resources:
            Tutorial : https://cp-algorithms.com/graph/depth-first-search.html
            
        >>> Implementation:
        
            const int N=200005;
            bool vis[N];
            int subtree[N];
            vector<int> adj[N];
            void dfs(int v) 
            {
                vis[v]=true;
                subtree[v]=1;
                for(int u:adj[v]) 
                {
                    if(!vis[u])
                    {
                        dfs(u);
                        subtree[v]+=subtree[u];
                    }
                }
            }