210. Course Schedule II

class Solution {
    public int[] findOrder(int numCourses, int[][] prerequisites) {
        int[] indegrees=new int[numCourses];
        int[][] graph=new int[numCourses][numCourses];
        
        for (int i=0;i<prerequisites.length;i++)
        {
            if(graph[prerequisites[i][1]][prerequisites[i][0]]==0)
                indegrees[prerequisites[i][0]]++;
            graph[prerequisites[i][1]][prerequisites[i][0]]=1;
        }
        
        Queue<Integer> que=new LinkedList<Integer>();
        for(int i=0;i<numCourses;i++)
            if(indegrees[i]==0)
                que.add(i);
        
        List<Integer> res=new ArrayList<Integer>();
        while(!que.isEmpty())
        {
            int c=que.poll();
            res.add(c);
            for(int i=0;i<numCourses;i++)
            {
                if(graph[c][i]==1)
                {
                    indegrees[i]--;
                    if(indegrees[i]==0)
                        que.add(i);
                }
            }
        }
        if(res.size()!=numCourses)
            return new int[0];
        int[] ret=new int[res.size()];
        for(int i=0;i<numCourses;i++)
            ret[i]=res.get(i);
        return ret;
    }
}