Course Schedule GFG

class Solution
{
  public:
    vector<int> findOrder(int n, int m, vector<vector<int>> prerequisites) 
    {
        //created adj
        vector<int> adj[n];
        for(auto it: prerequisites){
            adj[it[1]].push_back(it[0]);
        }
        //calculated the degree of nodes
        int inDegree[n] = {0};
        for(int i=0;i<n;i++){
            for(auto it: adj[i]) inDegree[it]++;
        }
        //push degree in queue having degree 0
        queue<int> q;
        for(int i=0;i<n;i++){
            if(inDegree[i] == 0) q.push(i);
        }
        
        vector<int> topo;
        while(!q.empty()){
            int node = q.front();
            q.pop();
            topo.push_back(node);
            for(auto it: adj[node]){
                inDegree[it]--;
                if(inDegree[it] == 0) q.push(it);
            }
        }
        if(topo.size() == n) return topo;
        return {};
    }
};