diameter of tree dp code example

Example: diameter of tree using dfs

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
class Solution {
public:
   map <int ,int > l;
   int best;
   int node;
   int dfs(int v, bool* visited, vector <int> graph[], int c = 0){
      visited[v] = true;
      int ans = 0;
      for(int i = 0; i < graph[v].size(); i++){
         if(!visited[graph[v][i]])ans = max(ans,dfs(graph[v][i], visited, graph, c+1));
      }
      if(c > best){
         best = c;
         node = v ;
      }
      visited[v] = false;
      return max(c,ans);
   }
   int treeDiameter(vector<vector<int>>& e) {
      int n = e.size();
      vector <int> graph[n+1];
      for(int i = 0; i < n; i++){
         graph[e[i][0]].pb(e[i][1]);
         graph[e[i][1]].pb(e[i][0]);
      }
      bool* visited = new bool[n+1]();
      best = 0;
      node = 0;
      dfs(0, visited, graph);
      bool* visited2 = new bool[n+1]();
      return dfs(node, visited2, graph);
   }
};
main(){
   vector<vector<int>> v = {{0,1},{1,2},{2,3},{1,4},{4,5}};
   Solution ob;
   cout <<ob.treeDiameter(v);
}