0 day streak0 XPP1
Write a function. Test real cases. Improve your solution.
links is a list of directed [from_node, to_node] pairs with string node names. Return a path from start to target with the fewest links, including both endpoints. If several shortest paths exist, return the lexicographically smallest whole path using Python's normal string ordering. Duplicate links and cycles are allowed. Return None when target is unreachable. When start equals target, return [start], even if it appears in no link. Direction matters: a link from A to B does not imply B to A. Inputs contain at most 100 different node names. Leave them unchanged.
[[["a", "b"], ["b", "c"], ["a", "c"]], "a", "c"]
["a", "c"]
[[["start", "beta"], ["beta", "end"], ["start", "alpha"], ["alpha", "end"]], "start", "end"]
["start", "alpha", "end"]
[[["a", "b"]], "b", "a"]
None
[[], "solo", "solo"]
["solo"]
[[["a", "b"], ["a", "b"], ["b", "a"], ["b", "c"]], "a", "c"]
["a", "b", "c"]
[[], "a", "z"]
None
[[["a", "b"], ["b", "d"], ["d", "z"], ["b", "c"], ["c", "z"]], "a", "z"]
["a", "b", "c", "z"]
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