力扣207、课程表 【图】

class Solution {
    public boolean canFinish(int numCourses, int[][] prerequisites) {
        List<Integer>[] adjacentArr = new List[numCourses];
        int[] indegrees = new int[numCourses];
        for (int i = 0; i < numCourses; i++) {
            adjacentArr[i] = new ArrayList<Integer>();
        }
        for (int[] prerequisite : prerequisites) {
            adjacentArr[prerequisite[1]].add(prerequisite[0]);
            indegrees[prerequisite[0]]++;
        }
        int finishCount = 0;
        Queue<Integer> queue = new ArrayDeque<Integer>();
        for (int i = 0; i < numCourses; i++) {
            if (indegrees[i] == 0) {
                queue.offer(i);
            }
        }
        while (!queue.isEmpty()) {
            int curr = queue.poll();
            finishCount++;
            List<Integer> adjacent = adjacentArr[curr];
            for (int next : adjacent) {
                indegrees[next]--;
                if (indegrees[next] == 0) {
                    queue.offer(next);
                }
            }
        }
        return finishCount == numCourses;
    }
}