class Solution {
    public int[] findOrder(int n, int[][] prerequisites) {


        int[] indegree= new int[n];


        Queue<Integer> q= new LinkedList<>();
        for(int[] i:prerequisites){
            indegree[i[0]]++;
        }

        int f=0;
        int[] res= new int[n];
        for(int i=0;i<n;i++){
        if(indegree[i]==0){
             res[f++]=i;
            q.add(i);
        }
        }

        while(!q.isEmpty()){
            int t= q.poll();
            for(int i=0;i<prerequisites.length;i++){
                if(t==prerequisites[i][1]){
                    indegree[prerequisites[i][0]]--;
                    if(indegree[prerequisites[i][0]]==0){
                        res[f++]=prerequisites[i][0];
                        q.add(prerequisites[i][0]);
                    }
                }
            }

        }

        return (f==n)?res:new int[0];
    }
}