// 39.33%
class Solution {
    public int[] findOrder(int numCourses, int[][] prerequisites) {
        int[] dc = new int[numCourses];
        ArrayList<ArrayList<Integer>> deps = new ArrayList<ArrayList<Integer>>();

        for (int i = 0; i < numCourses; i++) {
            deps.add(new ArrayList<Integer>());
        }

        for (int[] req: prerequisites) {
            deps.get(req[1]).add(req[0]);
            dc[req[0]] += 1;
        }


        int[] res = new int[numCourses];
        int rPos = 0;

        while (rPos < numCourses){
            boolean f = false;

            for (int node = 0; node < numCourses; node++) {
                if (dc[node] == 0) {
                    dc[node] = -1;
                    for (int d: deps.get(node)) dc[d] -= 1;

                    res[rPos++] = node;
                    f = true;
                }
            }

            if (!f) return new int[0];
        }

        return res;
    }
}