61 lines
1.5 KiB
Python
61 lines
1.5 KiB
Python
from collections import deque
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from cfg import config
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def prepare_dijkstra(connection):
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cursor = connection.cursor()
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cursor.execute('''INSERT OR IGNORE INTO dijkstra_helper(name)
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SELECT destination FROM links
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''')
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if(config["use_sqlite"]):
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cursor.execute("UPDATE dijkstra_helper SET value=1e1000")
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else:
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cursor.execute("UPDATE dijkstra_helper SET value=2147483647")
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connection.commit()
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def dijkstra_one(title, value, connection):
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cursor = connection.cursor()
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if(isinstance(title, tuple)):
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# Idk why this happens.
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title = title[0]
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cursor.execute('''SELECT name
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FROM dijkstra_helper
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LEFT JOIN links ON links.destination=dijkstra_helper.name
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WHERE links.source=:title
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AND dijkstra_helper.value>:value''', {"title": title, "value": value + 1})
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# This is the list of nodes that have to be updated
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result = cursor.fetchall()
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cursor.execute('''UPDATE dijkstra_helper
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SET value=:value
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WHERE name IN (
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SELECT destination
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FROM links
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WHERE source=:title)
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AND dijkstra_helper.value>:value''', {"value": value + 1, "title": title})
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connection.commit()
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return result
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def recursive_dijkstra(titles, value, connection):
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if(not titles):
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return
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todos = deque()
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for title in titles:
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todos.extend(dijkstra_one(title, value, connection))
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recursive_dijkstra(todos, value + 1, connection)
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def dijkstra(title, connection):
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cursor = connection.cursor()
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cursor.execute("UPDATE dijkstra_helper SET value=0 WHERE name=?", (title,))
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todos = dijkstra_one(title, 1, connection)
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recursive_dijkstra(todos, 2, connection)
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