课程表

解题思路：拓扑排序（实际上就是贪心算法）

class Solution {    public boolean canFinish(int numCourses, int[][] prerequisites) {        int len = prerequisites.length;        if(len==0){            return true;        }        int[] degree = new int[numCourses];        for(int[] p : prerequisites){            degree[p[0]]++;        }        LinkedList
     
       list = new LinkedList<>();        List
      
        res = new ArrayList<>();        for(int i=0;i