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author | Vincent Ambo <mail@tazj.in> | 2021-12-13T22·51+0300 |
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committer | Vincent Ambo <mail@tazj.in> | 2021-12-13T23·15+0300 |
commit | 019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch) | |
tree | 76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py | |
parent | 464bbcb15c09813172c79820bcf526bb10cf4208 (diff) | |
parent | 6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff) |
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208 git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py')
-rw-r--r-- | users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py b/users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py new file mode 100644 index 000000000000..03907f604044 --- /dev/null +++ b/users/wpcarro/scratch/data_structures_and_algorithms/dijkstra-shortest-path.py @@ -0,0 +1,48 @@ +from collections import deque +from heapq import heappush, heappop +from fixtures import weighted_graph + + +def put(t, x, xs): + if t == 'stack': + return xs.append(x) + if t == 'queue': + return xs.append(x) + if t == 'priority': + return heappush(xs, x) + + +def pop(t, xs): + if t == 'stack': + return xs.pop() + if t == 'queue': + return xs.popleft() + if t == 'priority': + return heappop(xs) + + +# shortest_path :: Vertex -> Vertex -> Graph -> [Vertex] +def shortest_path(a, b, g): + """Returns the shortest path from vertex a to vertex b in graph g.""" + t = 'priority' + xs = [] + seen = set() + # Map(Weight, [Vertex]) + m = {} + + put(t, (0, [a], a), xs) + + while xs: + w0, path, v = pop(t, xs) + + seen.add(v) + if v == b: + m[w0] = path + for w1, x in g.get(v): + if x not in seen: + put(t, (w0 + w1, path + [x], x), xs) + + return m + + +print(shortest_path('a', 'f', graph_a)) |