scientific-programming-exercises/exam/ex01/dijkstra.py

from collections import deque

from cfg import config
from db_util import get_page_id
import sql

def prepare_dijkstra(connection):
	cursor = connection.cursor()
	cursor.execute(sql.statements["dijkstra_insert_pages"])

	cursor.execute(sql.statements["dijkstra_set_infinity"])
	connection.commit()

def dijkstra_one(page, value, connection):
	cursor = connection.cursor()
	if(isinstance(page, tuple)):
		# Idk why this happens.
		title = title[0]
	cursor.execute(sql.statements["dijkstra_get_to_update"], (page, value + 1))
	# This is the list of nodes that have to be updated
	result = cursor.fetchall()

	cursor.execute(sql.statements["dijkstra_update"], (value + 1, page, value + 1))
	connection.commit()
	return result

def recursive_dijkstra(titles, value, connection):
	if(not titles):
		return

	todos = deque()
	for title in titles:
		todos.extend(dijkstra_one(title, value, connection))

	recursive_dijkstra(todos, value + 1, connection)


def dijkstra(title, connection):
	page = get_page_id(title, connection)
	cursor = connection.cursor()
	cursor.execute(sql.statements["dijkstra_set_root"], (page,))

	todos = dijkstra_one(page, 1, connection)
	recursive_dijkstra(todos, 2, connection)