86 lines
2.0 KiB
Python
86 lines
2.0 KiB
Python
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from math import inf
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class Edge:
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length = 0
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def __init__(self, start, end, length):
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self.length = length
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self.start = start
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self.end = end
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class Node:
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def __init__(self, xpos, ypos):
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self.xpos = xpos
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self.ypos = ypos
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class Graph:
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def __init__(self):
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self.edges = list()
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self.nodes = list()
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def add_node(self, xpos, ypos):
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self.nodes.append(Node(xpos, ypos))
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def add_edge(self, start_index, end_index, length):
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self.edges.append(Edge(start_index, end_index, length))
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def Dijkstra(graph, source_index, target_index):
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n = len(graph.nodes)
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if (target_index >= n):
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return None
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unvisited = list(range(n))
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distances_from_start = [inf] * n
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distances_from_start[source_index] = 0
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node_sequences = [list() for i in range(n)]
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node_sequences[source_index] = [source_index]
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while(True):
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try:
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current_index = min(unvisited, key = lambda i: distances_from_start[i])
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except ValueError:
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break
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if current_index == target_index:
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break
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unvisited.remove(current_index)
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for edge in filter(
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lambda e: e.start == current_index or e.end == current_index,
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graph.edges):
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start = current_index
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end = edge.end if edge.start == current_index else edge.start
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if end in unvisited and distances_from_start[end] > distances_from_start[start] + edge.length:
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distances_from_start[end] = distances_from_start[start] + edge.length
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node_sequences[end] = node_sequences[start].copy()
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node_sequences[end].append(end)
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return node_sequences[target_index]
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graph = Graph()
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graph.add_node(1, 2)
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graph.add_node(4, 7)
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graph.add_node(3,1)
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graph.add_node(-2,0)
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graph.add_node(0,0)
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graph.add_edge(0, 1, 1)
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graph.add_edge(1, 2, 2)
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graph.add_edge(2, 3, 3)
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graph.add_edge(3, 0, 1)
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graph.add_edge(1, 3, 3)
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print(Dijkstra(graph, 0, 5))
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