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Graph/2192.All_Ancestors_of_a_Node_in_a_Directed_Acyclic_Graph/Python/2192.All_Ancestors_of_a_Node_in_a_Directed_Acyclic_Graph.py

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+class Solution(object):
+    def getAncestors(self, n, edges):
+        """
+        :type n: int
+        :type edges: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        #===========================================#
+        # Depth-first search based traversal method #
+        #===========================================#
+
+        ############
+        #Initialize
+        ##### Length of edges array #####
+        len_edges = len(edges)
+
+        ##### Root-child array #####
+        root_child_arry = [[] for _ in range(n)]
+
+        ##### Result array #####
+        res_arry = [[] for _ in range(n)]
+
+
+        #############################################################
+        #Depth-first search based loop traversal with recorded array
+        ##### Step 1: Record indexed-nodes informations with array #####
+        for edges_idx in range(len_edges):
+            (root_child_arry[(edges[edges_idx])[0]]).append((edges[edges_idx])[1]) #Keep updating/recording
+
+        ##### Step 2: Looped-traversal with recorded array #####
+        for n_idx in range(n):
+            self.dfsTraversal(n_idx, n_idx, root_child_arry, res_arry) #Recursion function call
+
+        return res_arry
+
+
+    def dfsTraversal(self, curr_node, curr_value, root_child_arry, res_arry):
+        """
+        :type curr_node: int
+        :type curr_value: int
+        :type root_child_arry: List[List[int]]
+        :type res_arry: List[List[int]]
+        :rtype: None, void
+        """
+        #=============================================#
+        # Depth-first search based traversal function #
+        #=============================================#
+
+        ####################
+        #Whole process/flow
+        for next_node in root_child_arry[curr_node]:
+
+            ##### Check if the current-next nodes matched conditions or not #####
+            if ((not res_arry[next_node]) or ((res_arry[next_node])[(-1)] != curr_value)):
+                (res_arry[next_node]).append(curr_value) #Keep updating/recording
+
+                self.dfsTraversal(next_node, curr_value, root_child_arry, res_arry) #Recursion function call