019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
26 lines
711 B
Python
26 lines
711 B
Python
# Doing a practice implementation of Dijkstra's algorithm: a priority-first
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# search.
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from heapq import heappush, heappop
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class Node(object):
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def __init__(self, value, children):
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self.value = value
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self.children = children
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def shortest_path(a, b):
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"""Return the shortest path from `a` to `b`."""
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q = []
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seen = set()
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heappush((a.value, a, [a]), q)
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while q:
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d, node, path = heappop(q)
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if node == b:
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return path
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seen.add(node)
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for child in node.children:
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if child not in seen:
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heappush((d + child.value, child, path + [child]), q)
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raise Exception("Path between nodes A and B does not exist.")
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