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);
}