tree_all_pairs_lowest_common_ancestor(G, root=None, pairs=None)
Only defined on non-null trees represented with directed edges from parents to children. Uses Tarjan's off-line lowest-common-ancestors algorithm. Runs in time $O(4 \times (V + E + P))$ time, where 4 is the largest value of the inverse Ackermann function likely to ever come up in actual use, and $P$ is the number of pairs requested (or $V^2$ if all are needed).
Tarjan, R. E. (1979), "Applications of path compression on balanced trees", Journal of the ACM 26 (4): 690-715, doi:10.1145/322154.322161.
The root of the subtree to operate on. If None, assume the entire graph has exactly one source and use that.
The pairs of interest. If None, Defaults to all pairs of nodes under :None:None:`root` that have a lowest common ancestor.
in pairs
and :None:None:`lca` is their lowest common ancestor.
Yield the lowest common ancestor for sets of pairs in a tree.
all_pairs_lowest_common_ancestor
similar routine for general DAGs
lowest_common_ancestor
just a single pair for general DAGs
The following pages refer to to this document either explicitly or contain code examples using this.
networkx.algorithms.lowest_common_ancestors.all_pairs_lowest_common_ancestor
networkx.algorithms.lowest_common_ancestors.lowest_common_ancestor
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