# Copyright (c) 2007-2008 Pedro Matiello <pmatiello@gmail.com>

#

# Permission is hereby granted, free of charge, to any person

# obtaining a copy of this software and associated documentation

# files (the "Software"), to deal in the Software without

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# copies of the Software, and to permit persons to whom the

# Software is furnished to do so, subject to the following

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# The above copyright notice and this permission notice shall be

# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

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# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

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"""

Sorting algorithms for python-graph.

@sort: topological_sorting

"""

# Topological sorting

def topological_sorting(graph):

	"""

	Topological sorting.

	@attention: Topological sorting is meaningful only for directed acyclic graphs.

	@type  graph: graph

	@param graph: Graph.

	@rtype:  list

	@return: Topological sorting for the graph.

	"""

	# The topological sorting of a DAG is equivalent to its reverse postordering.

	tmp, tmp, post = graph.depth_first_search()

	post.reverse()

	return post