Update graphs/graph_list.py (#3813)

- update naming style to snake_case
- add type hints

Author: taseikyo

graphs/graph_list.py

@@ -7,34 +7,34 @@
 
 class AdjacencyList:
     def __init__(self):
-        self.List = {}
+        self.adj_list = {}
 
-    def addEdge(self, fromVertex, toVertex):
+    def add_edge(self, from_vertex: int, to_vertex: int) -> None:
         # check if vertex is already present
-        if fromVertex in self.List.keys():
-            self.List[fromVertex].append(toVertex)
+        if from_vertex in self.adj_list:
+            self.adj_list[from_vertex].append(to_vertex)
         else:
-            self.List[fromVertex] = [toVertex]
+            self.adj_list[from_vertex] = [to_vertex]
 
-    def printList(self):
-        for i in self.List:
-            print((i, "->", " -> ".join([str(j) for j in self.List[i]])))
+    def print_list(self) -> None:
+        for i in self.adj_list:
+            print((i, "->", " -> ".join([str(j) for j in self.adj_list[i]])))
 
 
 if __name__ == "__main__":
     al = AdjacencyList()
-    al.addEdge(0, 1)
-    al.addEdge(0, 4)
-    al.addEdge(4, 1)
-    al.addEdge(4, 3)
-    al.addEdge(1, 0)
-    al.addEdge(1, 4)
-    al.addEdge(1, 3)
-    al.addEdge(1, 2)
-    al.addEdge(2, 3)
-    al.addEdge(3, 4)
-
-    al.printList()
+    al.add_edge(0, 1)
+    al.add_edge(0, 4)
+    al.add_edge(4, 1)
+    al.add_edge(4, 3)
+    al.add_edge(1, 0)
+    al.add_edge(1, 4)
+    al.add_edge(1, 3)
+    al.add_edge(1, 2)
+    al.add_edge(2, 3)
+    al.add_edge(3, 4)
+
+    al.print_list()
 
     # OUTPUT:
     # 0 -> 1 -> 4