from typing import List

class Solution:
    # This is a Topological sort question and does not belong to DFS or BFS 
    def findSmallestSetOfVertices(self, n: int, edges: List[List[int]]) -> List[int]:
        indegree = {}
        result = []
        
       # all nodes will be in 0 indegree initially
        for i in range(n):
            indegree[i] = indegree.get(i, 0)

        # increase the node degree if another node points to it
        for a, b in edges:
            indegree[b] = indegree.get(b, 0)
            indegree[b] += 1

        # find all nodes with 0 degrees
        for edge, degree in indegree.items():
            if degree == 0:
                result.append(edge)
        return result