Course Schedule II

LeetCode: https://leetcode.com/problems/course-schedule-ii/

Return the ordering of courses you should take to finish all courses. If impossible, return an empty array.

1from collections import deque
2

3def findOrder(numCourses: int, prerequisites: List[List[int]]) -> List[int]:
4    graph = [[] for _ in range(numCourses)]
5    indeg = [0] * numCourses
6    for a, b in prerequisites:
7        graph[b].append(a)
8        indeg[a] += 1
9        
10    q = deque([i for i in range(numCourses) if indeg[i] == 0])
11    order = []
12    
13    while q:
14        cur = q.popleft()
15        order.append(cur)
16        for nxt in graph[cur]:
17            indeg[nxt] -= 1
18            if indeg[nxt] == 0:
19                q.append(nxt)
20    
21    return order if len(order) == numCourses else []
Next
Find All Possible Recipes from Given Supplies
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numCourses=4
prerequisites=Array(4)
graph=Array(4)
indeg=[0, 1, 1, 2]
Step 1 / 6
Step 1:
Build graph and indeg for prerequisites [[1,0],[2,0],[3,1],[3,2]].
Focus: select @ [0]
numCourses=4