def _test_shortest_paths(ds, algorithm):
import pydatastructs.utils.misc_util as utils
GraphNode = getattr(utils, "Adjacency" + ds + "GraphNode")
vertices = [GraphNode('S'), GraphNode('C'),
GraphNode('SLC'), GraphNode('SF'),
GraphNode('D')]
graph = Graph(*vertices)
graph.add_edge('S', 'SLC', 2)
graph.add_edge('C', 'S', 4)
graph.add_edge('C', 'D', 2)
graph.add_edge('SLC', 'C', 2)
graph.add_edge('SLC', 'D', 3)
graph.add_edge('SF', 'SLC', 2)
graph.add_edge('SF', 'S', 2)
graph.add_edge('D', 'SF', 3)
dist, pred = shortest_paths(graph, algorithm, 'SLC')
assert dist == {'S': 6, 'C': 2, 'SLC': 0, 'SF': 6, 'D': 3}
assert pred == {'S': 'C', 'C': 'SLC', 'SLC': None, 'SF': 'D', 'D': 'SLC'}
dist, pred = shortest_paths(graph, algorithm, 'SLC', 'SF')
assert dist == 6
assert pred == {'S': 'C', 'C': 'SLC', 'SLC': None, 'SF': 'D', 'D': 'SLC'}
graph.remove_edge('SLC', 'D')
graph.add_edge('D', 'SLC', -10)
assert raises(ValueError, lambda: shortest_paths(graph, 'bellman_ford', 'SLC'))
def _test_shortest_paths_negative_edges(ds, algorithm):
import pydatastructs.utils.misc_util as utils
GraphNode = getattr(utils, "Adjacency" + ds + "GraphNode")
vertices = [
GraphNode('s'),
GraphNode('a'),
GraphNode('b'),
GraphNode('c'),
GraphNode('d')
]
graph = Graph(*vertices)
graph.add_edge('s', 'a', 3)
graph.add_edge('s', 'b', 2)
graph.add_edge('a', 'c', 1)
graph.add_edge('b', 'd', 1)
graph.add_edge('b', 'a', -2)
graph.add_edge('c', 'd', 1)
dist, pred = shortest_paths(graph, algorithm, 's')
assert dist == {'s': 0, 'a': 0, 'b': 2, 'c': 1, 'd': 2}
assert pred == {'s': None, 'a': 'b', 'b': 's', 'c': 'a', 'd': 'c'}
dist, pred = shortest_paths(graph, algorithm, 's', 'd')
assert dist == 2
assert pred == {'s': None, 'a': 'b', 'b': 's', 'c': 'a', 'd': 'c'}
def _test_shortest_paths_negative_edges(ds, algorithm):
import pydatastructs.utils.misc_util as utils
GraphNode = getattr(utils, "Adjacency" + ds + "GraphNode")
vertices = [
GraphNode('1'),
GraphNode('2'),
GraphNode('3'),
GraphNode('4')
]
graph = Graph(*vertices)
graph.add_edge('1', '3', -2)
graph.add_edge('2', '1', 4)
graph.add_edge('2', '3', 3)
graph.add_edge('3', '4', 2)
graph.add_edge('4', '2', -1)
dist, next_v = shortest_paths(graph, algorithm, 's')
assert dist == {
'1': {
'3': -2,
'1': 0,
'4': 0,
'2': -1
},
'2': {
'1': 4,
'3': 2,
'2': 0,
'4': 4
},
'3': {
'4': 2,
'3': 0,
'1': 5,
'2': 1
},
'4': {
'2': -1,
'4': 0,
'1': 3,
'3': 1
}
}
assert next_v == {
'1': {
'3': '1',
'1': '1',
'4': None,
'2': None
},
'2': {
'1': '2',
'3': None,
'2': '2',
'4': None
},
'3': {
'4': '3',
'3': '3',
'1': None,
'2': None
},
'4': {
'2': '4',
'4': '4',
'1': None,
'3': None
}
}