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What is the problem of the level ancestor problem?
The level ancestor problem is the problem of preprocessing a given rooted tree T into a data structure that can determine the ancestor of a given node at a given depth from the root of the tree. Here depth of any node in a tree is the number of edges on the shortest path from the root of the tree to the node.
How to fill the ancestor matrix in dynamic programming?
Below is the algorithm to fill the ancestor matrix and depth of each node using dynamic programming. Here, we denote root node as R and initially assume the ancestor of root node as 0. We also initialize depth array with -1 means the depth of the current node is not set and we need to find its depth.
Which is the first level ancestor of node 8?
Based on the above algorithm 1st level ancestor of node 8 is ( depth (8)-1 )th ancestor of node 8. We have pre computed depth of each node and depth of 8 is 5 so we finally need to find (5-1) = 4th ancestor of node 8 which is equal to 21th ancestor of [21 ancestor of node 8] and 21th ancestor of node 8 is 20th ancestor of [20th ancestor of node 8].
How to get all ancestors of a node?
This will select all the rows from your table, where the target person you’re interested in is a descendant of – any level down the hierarchy. So this will find that target person’s immediate and non-immediate ancestors all the way up to the root.
What does getancestor do when there is no table?
GetAncestor returns the selected level in the hierarchy even if a table isn’t present. For example, the following code specifies a current employee and returns the hierarchyid of the ancestor of the current employee without reference to a table.
Which is an example of a getancestor in SQL Server?
GetAncestor (1) returns the employees that have david0 as their immediate ancestor (their parent). The following example uses GetAncestor (1). GetAncestor (2) returns the employees that are two levels down in the hierarchy from the current node. These employees are the grandchildren of the current node. The following example uses GetAncestor (2).