Split dijkstra.py into three files: node, edge, graph

utils/dijkstra.py

@@ -1,88 +0,0 @@
-from math import inf
-from typing import Iterator, Optional
-
-
-class Node:
-    def __init__(self, x: int, y: int):
-        self.x: int = x
-        self.y: int = y
-
-
-class Edge:
-    def __init__(self, start: int, end: int, length: float):
-        self.length: float = length
-        self.start: int = start
-        self.end: int = end
-
-
-class Graph:
-    def __init__(self):
-        self.edges: list[Edge] = []
-        self.nodes: list[Node] = []
-
-    def add_node(self, x: int, y: int) -> None:
-        self.nodes.append(Node(x, y))
-
-    def add_edge(self, start_index: int, end_index: int, length: float) -> None:
-        self.edges.append(Edge(start_index, end_index, length))
-
-    def edges_adjacent_to(self, node_i: int) -> Iterator[Edge]:
-        return filter(lambda e: e.start == node_i or e.end == node_i, self.edges)
-
-    def dijkstra(self, source_index: int, target_index: int) -> Optional[list[int]]:
-        n = len(self.nodes)
-
-        if source_index < 0 or source_index >= n:
-            return None
-
-        if target_index < 0 or target_index >= n:
-            return None
-
-        unvisited = list(range(n))
-
-        distances_from_start = [inf] * n
-        distances_from_start[source_index] = 0
-
-        node_sequences = [[] for _ in range(n)]
-        node_sequences[source_index] = [source_index]
-
-        while True:
-            current_index = min(unvisited, key=lambda i: distances_from_start[i])
-
-            if current_index == target_index:
-                break
-
-            unvisited.remove(current_index)
-
-            for edge in self.edges_adjacent_to(current_index):
-                start = current_index
-                end = edge.end if edge.start == current_index else edge.start
-
-                if end in unvisited and distances_from_start[end] > distances_from_start[start] + edge.length:
-                    distances_from_start[end] = distances_from_start[start] + edge.length
-                    node_sequences[end] = node_sequences[start].copy()
-                    node_sequences[end].append(end)
-
-        return node_sequences[target_index]
-
-
-def main() -> None:
-    graph = Graph()
-
-    graph.add_node(1, 2)
-    graph.add_node(4, 7)
-    graph.add_node(3, 1)
-    graph.add_node(-2, 0)
-    graph.add_node(0, 0)
-
-    graph.add_edge(0, 1, 1)
-    graph.add_edge(1, 2, 2)
-    graph.add_edge(2, 3, 3)
-    graph.add_edge(3, 0, 1)
-    graph.add_edge(1, 3, 3)
-
-    print(graph.dijkstra(0, 3))
-
-
-if __name__ == "__main__":
-    main()