class Solution {

public:

bool dfs(int curr, int parent, vector<vector<int>>& graph, vector<int>& visited){

if(visited[curr])

return false;

visited[curr] = 1;

for(int i = 0; i < graph[curr].size(); i++){

if(graph[curr][i] == parent)

continue;

if(dfs(graph[curr][i], curr, graph, visited) == false)

return false;

}

return true;

}

bool validTree(int n, vector<vector<int>> &edges) {

// write your code here

if(edges.size() != n - 1)

return false;

vector<vector<int>> graph (n);

vector<int> visited (n, 0);

for(int i = 0; i < edges.size(); i++){

int first = edges[i][0];

int second = edges[i][1];

graph[first].push_back(second);

graph[second].push_back(first);

}

if(dfs(0, -1, graph, visited) == false)

return false;

for(int i = 0; i < n; i++){

if(visited[i] == 0)

return false;

}

return true;

}

};