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UCS

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Safak
2025-04-15 17:24:18 +02:00
parent 370adb1234
commit 229fb4e4e2
2 changed files with 25 additions and 15 deletions
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2
graph.py
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@@ -7,7 +7,7 @@ class Node:
self.parent = None self.parent = None
self.name = name self.name = name
self.edges = [] self.edges = []
self.value = 0 self.value = 0 # cost reaching this node
class Edge: class Edge:

38
main.py
View File

@@ -21,43 +21,48 @@ romania = Graph( ['Or', 'Ne', 'Ze', 'Ia', 'Ar', 'Si', 'Fa',
] ) ] )
def search(graph, queue, start_node_name, target_node_name): def search(graph, queue, start_node_name, target_node_name):
cost = 0
visited_nodes = [] # Nodes which have been visited visited_nodes = [] # Nodes which have been visited
path = [] path = []
start_node = getNode(start_node_name, graph.nodes) start_node = getNode(start_node_name, graph.nodes)
target_node = getNode(target_node_name, graph.nodes) target_node = getNode(target_node_name, graph.nodes)
start_node.value = 0
queue.push(start_node) queue.push(start_node)
while not queue.empty(): while not queue.empty():
current_node = queue.pop() current_node = queue.pop()
visited_nodes.append(current_node.name) visited_nodes.append(current_node.name)
if current_node == target_node: if not current_node == target_node:
path.append(current_node.name)
tmp = current_node
while not tmp == start_node:
for edge in tmp.parent.edges:
if edge.end.name == tmp.name:
cost += edge.value
tmp = tmp.parent
path.insert(0, tmp.name) # reversed insertion
else:
for edge in current_node.edges: for edge in current_node.edges:
neighbor = edge.end neighbor = edge.end
condition = not visited_nodes.__contains__(neighbor.name)
new_cost = current_node.value + edge.value
# UCS
if queue.type == 'PRIO':
condition = not visited_nodes.__contains__(neighbor.name) and new_cost < neighbor.value
# works with digraph, because current_node is marked at this point, a cycle is not possible # works with digraph, because current_node is marked at this point, a cycle is not possible
if not visited_nodes.__contains__(neighbor.name): if condition:
queue.push(neighbor)
neighbor.parent = current_node neighbor.parent = current_node
neighbor.value = new_cost
queue.push(neighbor)
else:
path.append(current_node.name)
while not current_node == start_node:
current_node = current_node.parent
path.insert(0, current_node.name)
if path.__len__() == 0: if path.__len__() == 0:
print('zwischen ' + start_node_name + ' und ' + target_node_name + ' konnte kein Pfad gefunden werden') print('zwischen ' + start_node_name + ' und ' + target_node_name + ' konnte kein Pfad gefunden werden')
else: else:
print('From ' + start_node_name + ' to ' + target_node_name + ': ') print('From ' + start_node_name + ' to ' + target_node_name + ': ')
print('Path: ' + path.__str__().format()) print('Path: ' + path.__str__().format())
print('Cost: ' + cost.__str__()) print('Cost: ' + target_node.value.__str__())
def bfs(graph, start_node_name, target_node_name): def bfs(graph, start_node_name, target_node_name):
search(graph,Queue('FIFO'),start_node_name, target_node_name) search(graph,Queue('FIFO'),start_node_name, target_node_name)
@@ -65,9 +70,14 @@ def bfs(graph, start_node_name, target_node_name):
def dfs(graph, start_node_name, target_node_name): def dfs(graph, start_node_name, target_node_name):
search(graph,Queue('LIFO'),start_node_name, target_node_name) search(graph,Queue('LIFO'),start_node_name, target_node_name)
def utc(graph, start_node_name, target_node_name):
search(graph,Queue('PRIO'),start_node_name, target_node_name)
def main(): def main():
bfs(romania, 'Ti', 'Bu') bfs(romania, 'Ti', 'Bu')
dfs(romania, 'Ti', 'Bu') dfs(romania, 'Ti', 'Bu')
utc(romania, 'Or', 'Si')
if __name__ == "__main__": if __name__ == "__main__":
main() main()