class Solution {    public int[] findOrder(int numCourses, int[][] prerequisites) {        if(numCourses == 0) {            return new int[0];        }                Map
     
      > dependencies = new HashMap<>();        int[] connections = new int[numCourses];        for (int[] pair : prerequisites) {            if (!dependencies.containsKey(pair[1])) {                dependencies.put(pair[1], new ArrayList<>());            }            dependencies.get(pair[1]).add(pair[0]);            connections[pair[0]]++;        }                int[] result = new int[numCourses];        int runner = 0;                Queue
      
        queue = new LinkedList<>();        for (int i = 0; i < numCourses; i++) {            if (connections[i] == 0) {                queue.offer(i);            }        }                while (!queue.isEmpty()) {            int parent = queue.poll();            result[runner++] = parent;            if (dependencies.containsKey(parent)) {                for (int child : dependencies.get(parent)) {                    if (connections[child]-- == 1) {                      queue.offer(child);                    }                }            }        }        return runner == numCourses ? result : new int[0];    }}