Et-forest data structure implementation.
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This package implements ET forest data structure. Each tree in
the structure maintains a tree structure and offers logarithmic time
for tree operations (insertion and removal of nodes and edges) and
poly-logarithmic time for nearest common ancestor.
ET tree stores its structure as a sequence of symbols obtained
by dfs(root)
dfs (node)
{
s = node;
for each child c of node do
s = concat (s, c, node);
return s;
}
For example for tree
1
/ | \
2 3 4
/ |
4 5
the sequence is 1 2 4 2 5 3 1 3 1 4 1.
The sequence is stored in a slightly modified splay tree.
In order to support various types of node values, a hashtable
is used to convert node values to the internal representation.
The node representing the node in an et tree.