1361. Validate Binary Tree Nodes

class Solution {
public:
    bool ans = 1;
    vector<int> topo(int V, vector<int> adj[],vector<int>&ans) 
	{
	    vector<int>indeg(V,0);
	    for(int i = 0; i < V; i++){
	        for(auto x : adj[i]){
	            indeg[x]++;
	        }
	    }
	    queue<int>q;
	    for(int i = 0; i < V ;i++){
	        if(indeg[i] == 0){
	            q.push(i);
	        }
	    }
	    while(!q.empty()){
	        int node = q.front();
	        q.pop();
	        ans.push_back(node);
	        
	        for(auto x : adj[node]){
	            indeg[x]--;
	            if(indeg[x] == 0) q.push(x);
	        }
	        
	    }
	    return ans;
	}

    void dfs(int ind,vector<int> &vis,vector<int> adj[]){
        vis[ind] = 1;

        for(int i = 0; i < adj[ind].size(); i++){
            if(!vis[adj[ind][i]]){
                dfs(adj[ind][i], vis, adj);
            }else{
                ans = 0;
            }
        }
    }
    bool validateBinaryTreeNodes(int n, vector<int>& leftChild, vector<int>& rightChild) {
        
        vector<int> adj[n];
        vector<int> topoSort;
        for(int i = 0; i < n ;i++){
            if(leftChild[i] != -1)
            adj[i].push_back(leftChild[i]);
            if(rightChild[i] != -1)
            adj[i].push_back(rightChild[i]);
        }

        topo(n,adj,topoSort);
        if(topoSort.size() != n)return false;

        vector<int>vis(n,0);
        int ct = 0;
        for(auto x: topoSort)cout<<x<<" ";

        for(int i = 0; i < topoSort.size(); i++){
            if(!vis[topoSort[i]]){
                dfs(topoSort[i] ,vis ,adj);
                ct ++;
            }
        }
        cout<<ct <<endl;
        if(ct > 1)return false;
        return ans;

    }
};