import collections
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from typing import Mapping
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from pygraph.graphdemo import Graph
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def bfs(g: Graph, start: int) -> Graph:
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"""
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:param g:
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:param start:
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:return:
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"""
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tree = Graph()
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queue = collections.deque()
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VISITED = "visited"
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not_visited = {VISITED: False}
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visited = {VISITED: True}
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g.for_each_vertices(lambda v : g.merge_attribute(v, not_visited))
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queue.append(start) # append() is the enqueue() operation of a Queue
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g.merge_attribute(start, visited)
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while queue:
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u = queue.popleft() # popleft() is the dequeue() operation of a Queue
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for v in g.adjacent_of(u):
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if not g.get_attribute(v)[VISITED]:
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tree.add_edge(u, v)
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g.merge_attribute(v, visited)
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queue.append(v)
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return tree
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def bfs_dict(g: Graph, start: int) -> Mapping[int, int|None]:
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tree = {start:None}
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queue = collections.deque()
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VISITED = "visited"
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not_visited = {VISITED: False}
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visited = {VISITED: True}
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g.for_each_vertices(lambda v : g.merge_attribute(v, not_visited))
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queue.append(start) # append() is the enqueue() operation of a Queue
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g.merge_attribute(start, visited)
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while queue:
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u = queue.popleft() # popleft() is the dequeue() operation of a Queue
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for v in g.adjacent_of(u):
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if not g.get_attribute(v)[VISITED]:
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tree[v] = u
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g.merge_attribute(v, visited)
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queue.append(v)
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return tree
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pass
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def find_path(g: Graph, u: int, v: int) -> list[int]:
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tree = bfs_dict(g, v)
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path = [u]
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while (current := path[-1]) != v:
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precedent = tree[current]
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path.append(precedent)
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return path
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def find_path_gpt(g: Graph, u: int, v: int) -> list[int]:
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# Erstelle einen BFS-Baum, beginnend bei Knoten v
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bfs_tree = bfs_dict(g, v)
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# Wenn u nicht in bfs_tree ist, gibt es keinen Pfad von u nach v
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if u not in bfs_tree:
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return [] # Kein Pfad gefunden
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# Den Pfad von u nach v rekonstruieren
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path = []
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current = u
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while current is not None:
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path.append(current)
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current = bfs_tree[current]
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# Den Pfad umkehren, da wir rückwärts von u nach v gehen
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path.reverse()
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return path
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