210 course schedule ii
210. Course Schedule II
题目: https://leetcode.com/problems/course-schedule-ii/
难度: Medium
思路：
在207的基础上加了order，进击
class Solution(object):
def findOrder(self, numCourses, prerequisites):
"""
:type numCourses: int
:type prerequisites: List[List[int]]
:rtype: List[int]
"""
degrees = [ 0 for i in range(numCourses)]
childs = [[] for i in range(numCourses)]
for front, tail in prerequisites:
degrees[front] += 1
childs[tail].append(front)
courses = set(range(numCourses))
flag = True
order = []
while flag and len(courses):
flag = False
removeList = []
for x in courses:
if degrees[x] == 0:
print x
for child in childs[x]:
degrees[child] -= 1
removeList.append(x)
order.append(x)
flag = True
for x in removeList:
courses.remove(x)
if len(courses) == 0:
return order
else:
return []
