16 lines
513 B
Ruby
16 lines
513 B
Ruby
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# Find the lowest common ancestor in a Binary Tree.
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# The lowest common ancestor of two nodes v and w in a tree is the lowest (i.e. deepest) node
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# that has both v and w as descendants.
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def lowest_common_ancestor(node1, node2)
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parents = Set.new
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parent1 = node1.parent
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parent2 = node2.parent
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until parents.include?(parent1) || parents.include?(parent2)
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parents.merge [parent1, parent2]
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parent1 = parent1.parent
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parent2 = parent2.parent
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end
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parents.include? parent1 ? parent1 : parent2
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end
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