70 lines
2.4 KiB
Python
70 lines
2.4 KiB
Python
from math import inf
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from typing import Iterator, Optional
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from src.graph.node import Node
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from src.graph.edge import Edge
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class Graph:
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def __init__(self):
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self.edges: list[Edge] = []
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self.nodes: list[Node] = []
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def add_node(self, x: int, y: int, name: str) -> None:
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self.nodes.append(Node(x, y, name))
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def add_edge(self, start_index: int, end_index: int, length: float) -> None:
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self.edges.append(Edge(start_index, end_index, length))
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def number_of_nodes(self) -> int:
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return len(self.nodes)
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def get_edge(self, node_1: int, node_2: int) -> int:
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for edge in self.edges:
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if (edge.start == node_1 and edge.end == node_2) or (edge.start == node_2 and edge.end == node_1):
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return self.edges.index(edge)
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return -1
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def get_edge_nodes(self, edge: Edge) -> tuple[Node, Node]:
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return self.nodes[edge.start], self.nodes[edge.end]
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def edges_adjacent_to(self, node_i: int) -> Iterator[Edge]:
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return filter(lambda e: e.start == node_i or e.end == node_i, self.edges)
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def edge_exists(self, node_1: int, node_2: int) -> bool:
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return self.get_edge(node_1, node_2) != -1
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def dijkstra(self, source_index: int, target_index: int) -> Optional[list[int]]:
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n = len(self.nodes)
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if source_index < 0 or source_index >= n:
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return None
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if target_index < 0 or target_index >= n:
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return None
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unvisited = list(range(n))
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distances_from_start = [inf] * n
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distances_from_start[source_index] = 0
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node_sequences = [[] for _ in range(n)]
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node_sequences[source_index] = [source_index]
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while True:
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current_index = min(unvisited, key=lambda i: distances_from_start[i])
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if current_index == target_index:
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break
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unvisited.remove(current_index)
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for edge in self.edges_adjacent_to(current_index):
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start = current_index
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end = edge.end if edge.start == current_index else edge.start
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if end in unvisited and distances_from_start[end] > distances_from_start[start] + edge.length:
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distances_from_start[end] = distances_from_start[start] + edge.length
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node_sequences[end] = node_sequences[start].copy()
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node_sequences[end].append(end)
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return node_sequences[target_index] |