added multiple selection and corresponding features

src/graph/edge.py

@@ -1,5 +1,6 @@
 class Edge:
-    def __init__(self, start: int, end: int, length: float):
+    def __init__(self, start: int, end: int, length: float, index: int):
         self.length: float = length
         self.start: int = start
-        self.end: int = end
+        self.end: int = end
+        self.index: int = index

src/graph/graph.py

@@ -10,10 +10,10 @@ class Graph:
         self.nodes: list[Node] = []
 
     def add_node(self, x: int, y: int, name: str) -> None:
-        self.nodes.append(Node(x, y, name))
+        self.nodes.append(Node(x, y, name, len(self.nodes)))
 
     def add_edge(self, start_index: int, end_index: int, length: float) -> None:
-        self.edges.append(Edge(start_index, end_index, length))
+        self.edges.append(Edge(start_index, end_index, length, len(self.edges)))
 
     def number_of_nodes(self) -> int:
         return len(self.nodes)

src/graph/node.py

@@ -1,5 +1,6 @@
 class Node:
-    def __init__(self, x: int, z: int, name: str):
+    def __init__(self, x: int, z: int, name: str, index: int):
         self.x: int = x
         self.z: int = z
+        self.index: int = index
         self.name: str = name